Short answer. Yes, by default. When you name some heirs individually and others collectively, Article 847 treats the members of the group as if each had been instituted individually. Each one counts as a separate heir for dividing the estate — unless it clearly appears from the will that you intended the group to be treated differently.
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 →
The group is broken into individuals
The article addresses a mixed institution — some heirs named one by one, others lumped together as a class. Its example is a testator who says, "I designate as my heirs A and B, and the children of C." Article 847 provides that those collectively designated shall be considered as individually instituted, unless it clearly appears that the intention of the testator was otherwise. So the children of C are not treated as a single unit taking one combined share. Instead, each child is counted as a separate heir, standing on the same footing as A and B. The group dissolves into its individual members for purposes of the institution.
Why this changes the shares
How the group is counted directly affects who gets how much. If "the children of C" were treated as one heir, the whole group would share a single portion between them. Counting each child individually instead means every child takes a full share alongside the individually named heirs. Say there are two children of C: with A and B, that makes four heirs, and the estate divides into four, not three. The default in Article 847 therefore tends to enlarge what the members of the group receive, because each of them is a full participant rather than a fraction of one.
The exception: a clear contrary intention
This is only a default rule, and the testator can displace it. The article applies unless it clearly appears that the intention of the testator was otherwise. If the will shows that you meant the group to take a single collective share — for instance by fixing one portion for "the children of C" together — that intention prevails. The law simply supplies the most likely meaning when the will is silent on the point. To avoid the individual-counting default, the will must make the different intention clear; a vague or ambiguous phrasing will fall back to treating each member individually.
Draft with the outcome in mind
The lesson for anyone making a will is to be deliberate about grouped beneficiaries. If you want a class such as "my nephews" or "the children of C" to divide one share among themselves, say so plainly, because the law will otherwise hand each of them a full share. Conversely, if you are content for each member to count individually, the default already does that for you. Either way, spelling out your intention prevents the members of the group from receiving more — or less — than you actually meant them to have.