Short answer. Individually, in the usual case. Article 847 says that where a testator names some heirs individually and others collectively — 'A and B, and the children of C' — the collectively designated persons are treated as individually instituted, unless the will clearly shows he intended otherwise. Each child of C takes an equal share alongside A and B.
What the law says
those collectively designated shall be considered as individually instituted, unless it clearly appears that the intention of the testator was otherwise.
Civil Code, Article 847 — Individually and Collectively Named Heirs. Read the full provision →
What Article 847 lays down
Article 847 addresses a will that names some heirs individually and others collectively — its own example is 'I designate as my heirs A and B, and the children of C.' It then directs that those collectively designated shall be considered as individually instituted, unless it clearly appears that the intention of the testator was otherwise. The question it answers is one of counting heads. Does 'the children of C' form a single unit that takes one share between them, or does each child count as a separate heir? The article's default is the second: each is treated as though named on his own.
How the shares actually fall
On the default reading, you total the heads. If C has three children, the will has instituted five heirs in all — A, B, and each of the three — and, absent stated proportions, the estate or free portion is divided into five equal shares. The collective phrase is only a shorthand for listing them; it does not bundle them into one A-and-B-sized portion. This matters most where one branch is described collectively and the others by name, because reading the group as a single share would quietly cut each of its members down to a fraction of what an individually named heir receives.
When the presumption gives way
The rule is a presumption, not a straitjacket. It yields where it clearly appears that the intention of the testator was otherwise — for instance, if the will says the children of C are to take the share their father would have received, or fixes a single portion for the group and directs them to divide it among themselves. The word 'clearly' sets the bar: an ambiguous phrase is read the default way, and only language that plainly signals a collective, per-group share displaces it. So the drafter who really means one portion for a branch must say so in terms that leave no doubt.
Reading a will like this in practice
When working out who gets what under such a clause, first separate the individually named heirs from any collective description, then count every member of the collective as a distinct heir unless the will unmistakably says otherwise. Identify the members of the group as of the moment the will speaks, and check for any words fixing proportions, because express shares override the equal-division default. Where the wording is genuinely unclear, the estate is better settled with advice than by one branch asserting the reading that favours it.