Short answer. Yes, but only as a second option after your surviving grandparent. The Family Code provides that when there are no parents and no court-appointed guardian, substitute parental authority passes first to the surviving grandparent, and then to the oldest brother or sister over 21 years old — unless they are unfit or disqualified.

What the law says

The oldest brother or sister, over twenty-one years of age, unless unfit or disqualified

Family Code, Article 216 — Order of Substitute Parental Authority. Read the full provision →

The order of substitute parental authority

Article 216 of the Family Code sets out a ranked list of who may exercise substitute parental authority when parents are absent and no guardian has been appointed by a court. The order is: first, the surviving grandparent; second, the oldest brother or sister, over twenty-one years of age, unless unfit or disqualified; and third, the child's actual custodian, over twenty-one years of age, unless unfit or disqualified. Your oldest sibling may step into this role, but only if there is no surviving grandparent who is able and qualified to do so.

What substitute parental authority means

Substitute parental authority carries the same basic duties that parents would otherwise have: care, custody, education, and representation of the child in legal matters. The person exercising it stands in the place of the parents for as long as the situation requires it. It is not a permanent arrangement — if a parent returns or a guardian is later appointed by a court, the substitute arrangement gives way. Substitute parental authority also extends to decisions about the child's property when a court appointment becomes necessary, following the same order of preference.

The age and fitness conditions

Your oldest sibling must be over twenty-one years of age to qualify. A sibling who is younger cannot exercise substitute parental authority under this provision, regardless of how capable they are. Beyond the age requirement, the sibling must not be unfit or disqualified. Unfitness or disqualification can arise from various circumstances — a sibling who has been stripped of parental authority over their own children, who has a serious mental illness, or who has been convicted of certain crimes may be considered unfit. The article does not exhaustively define these terms; the assessment depends on facts.

Grandparents come first

It is easy to overlook that the surviving grandparent ranks above your oldest sibling in Article 216's order. If a grandparent is alive, present, and not unfit, they are the first choice under the law. The sibling's role is secondary. In a situation where multiple grandparents and siblings are all potentially available, Article 216 directs the decision: the grandparent steps in first, and the sibling only takes over if there is no grandparent in a position to do so. This hierarchy reflects the Family Code's preference for the closest generational relative to fill the parental role.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.