Short answer. Together, not in sequence. Article 849 says that when a testator calls a person and his children to the succession, they are all deemed instituted simultaneously and not successively. So naming 'Pedro and his children' means Pedro and the children inherit together, at the same time, rather than Pedro taking first and the children only afterward.
What the law says
When the testator calls to the succession a person and his children they are all deemed to have been instituted simultaneously and not successively.
Civil Code, Article 849 — A Person and His Children. Read the full provision →
An interpretive rule for an ambiguous phrase
A phrase like naming a person and his children as heirs can be read two ways. It might mean the person inherits first and the children only later, in succession to him, or it might mean the person and the children all inherit at once, together. Article 849 removes the doubt, providing that when the testator calls to the succession a person and his children they are all deemed to have been instituted simultaneously and not successively. The law supplies a default reading so that such an institution does not have to be litigated every time a will is worded this way.
Simultaneous, not successive
The rule chooses the simultaneous reading. The named person and his children are treated as co-heirs instituted at the same time, each taking a share of the inheritance directly, rather than the children waiting to receive the property only after the named person. This matters because a successive arrangement, where one takes and then passes to another, would resemble a substitution or a burden that the law does not presume from this simple wording. By defaulting to simultaneous institution, Article 849 keeps the disposition straightforward: all of them are heirs now.
How they share
Being instituted simultaneously, the person and his children take together, and in the absence of a contrary indication they generally share per capita, that is, by equal individual portions among all of them counted as heirs. The named person does not take a larger, separate slice on top of the children's shares merely by being mentioned first; all are co-heirs in the same institution. Of course, a testator who actually intends something different, such as giving the parent a life interest with the children to follow, can say so expressly, and clear contrary wording would override this default.
Why the default makes sense
The simultaneous reading reflects the more natural and less burdensome interpretation of a testator who lumps a person together with that person's children in one breath. It avoids reading a complex successive scheme into ordinary language, which would tie up the property and delay the children's enjoyment on the strength of an ambiguous phrase. For anyone reading such a will, Article 849 gives the answer: absent clear words to the contrary, the person and his children inherit together and at once, not one after the other.