Executive Summary

In Philippine succession law, grandchildren may inherit from a grandparent through their mother by the doctrine of representation. If the decedent’s daughter (the grandchildren’s mother) predeceased, was disinherited on a valid ground, or is otherwise incapacitated, her children step into her place and collectively take the share she would have received (the stirps). The exact shares depend on who else survives (e.g., other children of the decedent, the surviving spouse, and any illegitimate children). Status matters: legitimate vs. illegitimate filiation controls who can represent and how much they receive. Donations made by the grandparent to the maternal line during life may be collated and reduced to protect compulsory shares.

Core Doctrines

1) Representation in the Direct Descending Line

When it applies: If the decedent’s daughter (the predecessor-in-interest) died before the grandparent, was validly disinherited, or is incapacitated (e.g., unworthy), her children represent her.
Effect: The representatives collectively receive what their mother would have gotten. Within the stirps, they divide equally.
When it does not apply: If the mother is alive and capable, the grandchildren do not inherit in her place (no representation).

2) Compulsory Heirs and Legitimes

Compulsory heirs in the direct line (legitimate children/descendants) have a reserved portion (legitime) that cannot be impaired.
With descendants, the aggregate legitime of legitimate descendants is ½ of the estate; the free portion is the rest (subject to other compulsory heirs, like the spouse and acknowledged illegitimate children).
A surviving spouse has a legitime equal to the share of one legitimate child (which further consumes the free portion).

3) The Stirps Rule (Maternal Branch)

The maternal branch (stirps) stands in for the predeceased daughter.
Example (simple): Decedent leaves two branches—(A) living son; (B) predeceased daughter represented by her two children. The estate (after debts/charges) is divided by branches: ½ to A; ½ to the maternal branch (B), then split equally between the two grandchildren.

Status Rules Affecting Maternal-Line Grandchildren

A) Legitimate Grandchildren (through a legitimate daughter)

They are compulsory heirs by representation and inherit as if their mother lived, subject to the spouse/other heirs’ legitimes and valid lifetime donations.

B) Illegitimate Grandchildren (through a legitimate daughter)

The long-standing “iron curtain” rule bars intestate succession between an illegitimate person and the legitimate relatives of his/her parents.
Practical consequence: An illegitimate grandchild cannot inherit ab intestato from a legitimate grandparent through the legitimate mother by representation.
Testate workarounds: A grandparent may still give to such a grandchild by will or donation within the free portion; but representation for legitimes in intestacy is blocked by the iron curtain.

C) Grandchildren of/through an illegitimate maternal line

If the maternal line to the grandparent is illegitimate, intestate rights between that line and the grandparent’s legitimate relatives are restricted by the same iron curtain principle.
Particular outcomes turn on each person’s status (legitimate/illegitimate), whether succession is testate (free portion gifts possible) or intestate, and on who else survives.

D) Adopted Relationships

An adopted daughter is treated as a legitimate child of the adopter. Her children are descendants through her; the stirps analysis applies normally (subject to their own legitimacy status and the iron curtain vis-à-vis other legitimate relatives where relevant).

Tip: Always establish filiation first (civil registry, legitimation/adoption, acknowledgment), because status controls both the right to represent and the quantum of shares.

Concurrence Scenarios (Maternal-Line Focus)

Assume net hereditary estate (assets minus debts/charges). “Maternal branch” = the predeceased daughter’s stirps.

1) Survivors: One living son + maternal branch (two grandchildren), no spouse

Intestate: Estate split by heads/branches among legitimate children/lines →
- Son: ½
- Maternal branch: ½, then ¼ each grandchild.

2) Survivors: Maternal branch (three grandchildren) + surviving spouse, no other children

Legitime math (testate or intestate baseline):
- Legitimate descendants’ aggregate legitime: ½ of estate → belongs to maternal branch (since they represent the only child). Within the branch, divide equally among the three grandchildren.
- Spouse’s legitime: equal to one legitimate child’s share (taken from the free portion).
- Free portion: Whatever remains after these legitimes; if small, the spouse’s legitime may substantially reduce it.

3) Survivors: Maternal branch (two grandchildren) + two living children + spouse

Framework:
- Treat the maternal branch as one child for branch-counting. Thus, “children” = 3 (two living + one branch).
- Children’s aggregate legitime: ½ of estate, shared equally by three branches → each branch gets 1/6; the maternal branch’s 1/6 is then split between the two grandchildren (1/12 each).
- Spouse’s legitime = share of one child = 1/6.
- Free portion = ⅓ (subject to testamentary dispositions or intestate distribution).

4) Illegitimate grandchildren attempting to represent a legitimate daughter

Intestate: No representation to the legitimate grandparent due to the iron curtain; they cannot take their mother’s legitime as representatives.
Testate: The grandparent may give from the free portion (but cannot impair the legitimes of compulsory heirs).

Will-Based Issues (Maternal Line)

1) Preterition

If a will totally omits the maternal branch (because the daughter is not alive and her line is also omitted), the institution of heirs is annulled insofar as it affects compulsory heirs in the direct line; intestacy rules then restore the branch’s rightful share.

2) Reduction of Inofficious Dispositions

Lifetime donations or testamentary gifts that invade legitimes (e.g., gifts all to other children, none to the maternal branch) are reduced to respect the branch’s legitime.

3) Collation (Hotchpot)

Lifetime donations to the maternal line (to the daughter before death, or to her children) are brought back into the mass to compute proper shares; the donee keeps the gift but may receive less (or nothing) from the remainder if already fully satisfied.

Procedural Roadmap for Maternal-Line Grandchildren

Establish filiation and status
- Secure birth certificates, documents of legitimation/adoption/acknowledgment.
- Identify whether succession is testate (there’s a will; file/participate in probate) or intestate (petition for settlement of estate).
Inventory & debts first
- Determine conjugal/community vs. exclusive property of the decedent; exclude the spouse’s share outside the estate before computing legitimes.
Assert representation
- Plead that your mother predeceased/was incapacitated and that you represent her stirps. Name all co-branches.
Demand collation & reduction (if needed)
- List lifetime donations to siblings/other branches; seek collation and reduction of inofficious gifts.
Partition
- After accounting and legitime computations, partition by branches, then divide within the maternal branch.
If status blocks intestacy (iron curtain)
- Explore will-based (free portion) bequests, compromise, or claims outside succession (e.g., reimbursement, trusts)—but do not rely on representation in intestacy where barred.

Worked Mini-Examples

Example A (Maternal branch vs. one living child)

Net estate ₱12,000,000; survivors: living son S, and maternal branch M (two grandchildren G1, G2); no spouse.
Intestate: S = ₱6,000,000. M-branch = ₱6,000,000 → G1 = ₱3,000,000; G2 = ₱3,000,000.

Example B (Spouse present; one maternal branch only)

Net estate ₱9,000,000; survivors: spouse W; maternal branch M (three grandchildren).
Descendants’ aggregate legitime = ½ × 9M = ₱4.5M → M-branch gets ₱4.5M → ₱1.5M each to the three grandchildren.
Spouse’s legitime = equal to one child’s share. Here, with only one “child” (the branch), W’s legitime effectively consumes most of the free portion (computation depends on whether dispositions exist). Remainder = free portion.

Example C (Illegitimate grandchildren through a legitimate daughter)

Net estate ₱10,000,000; survivors: spouse + two living legitimate children; the predeceased daughter’s two children are illegitimate.
Intestate: The illegitimate grandchildren cannot represent the legitimate daughter vis-à-vis the legitimate grandparent (iron curtain). Distribution proceeds among the spouse and the two living children only.
Testate: The grandparent could have instituted legacies to the illegitimate grandchildren from the free portion, but not to impair legitimes.

Common Pitfalls in Maternal-Line Claims

Skipping status proof (legitimate/illegitimate/adopted).
Ignoring property regime (computing on the whole, instead of the decedent’s net half after conjugal/community dissolution).
Overlooking lifetime gifts to other branches (failure to seek collation).
Assuming representation even when the mother is alive (not allowed).
Assuming intestate rights despite the iron curtain where it applies.

Practical Checklist

Death certificate, marriage property regime evidence, asset–debt inventory.
Mother’s death/disinheritance/incapacity documents.
Birth certificates proving the maternal line; status documents (legitimation/adoption/acknowledgment).
Evidence of lifetime donations to any branch; request collation.
If a will exists, enter probate; raise preterition and reduction as needed.
Compute stirps first; then divide within the maternal branch.
If barred by status (iron curtain), evaluate free-portion bequests, settlement, or non-successional claims.

Bottom Line

Grandchildren may inherit through their maternal line by representation when their mother cannot inherit (predeceased, disinherited, incapacitated).
The maternal branch receives exactly the share the mother would have taken, then splits it internally.
Status controls: legitimate grandchildren fully represent; illegitimate grandchildren are barred from intestate representation to a legitimate grandparent under the iron curtain rule, though free-portion gifts by will/donation remain possible.
Use collation, reduction, and preterition doctrines to protect the branch’s legitimes, and compute shares after sorting property regimes and debts.

This article outlines Philippine rules on inheriting via the maternal line. For live estates, run the numbers with actual documents, property classifications, and family statuses to avoid costly errors.