Short answer. No. When a stranger gives support to someone without the knowledge of the person legally obliged to provide it, the giver may generally claim reimbursement from that person, but the right does not exist at all if it appears the support was given without any intention of being reimbursed, and that intention cannot simply be reversed afterward.
What the law says
unless it appears that he gave it without intention of being reimbursed
Family Code, Article 206 — Reimbursing a Stranger Who Gave Support. Read the full provision →
The general right of a stranger who gives support
Support is ordinarily owed by specific people to specific relatives — parents to children, spouses to each other, and similar relationships the law recognizes. When someone outside that obligation, a stranger to the duty, steps in and gives support without the knowledge of the person who was actually obliged to give it, the law lets that stranger claim reimbursement from the person who should have paid. This prevents the obligated party from being unjustly enriched simply because someone else covered a duty that was theirs to begin with. Both elements matter under the article: the support must come from someone outside the obligation, and it must have been given without the knowledge of the person obliged — that is the exact situation the reimbursement right is written for.
The exception: support given without intent to be reimbursed
That right to reimbursement is not unconditional. It disappears entirely if it appears the stranger gave the support without any intention of being reimbursed — in other words, if the support was meant as a gift rather than an advance to be recovered later. Once that intention is established, the person who gave the support has no claim against the person who was legally obliged to provide it, because the law treats the giving as a completed act of generosity, not a loan. How that intention appears is a matter of evidence: what you said to the family at the time, how the payments were framed, whether anything was documented as a loan. The article asks what the circumstances show, not what either side privately assumed.
Why you cannot reverse that intention afterward
If you supported a relative's child and made clear at the time that you did not expect to be paid back, that stated intention is what determines whether a right to reimbursement ever existed in the first place. The provision looks at whether the support appears to have been given without intent to be reimbursed, which points to the circumstances and statements surrounding the giving itself, not to a decision made afterward. Changing your mind later does not retroactively convert a gift into a claim the law never gave you against the obligated party.