Does this child have a sacramental record of his baptism? If not, a sacramental record of the baptism will need to be established and can be done by conditional baptism. In a conditional baptism, the priest begins the baptismal formula by saying, “If you are not already baptized, I baptize you…” If there is no sacramental record, or if you cannot obtain the child’s sacramental record from the parish at which the orphanage had the baby baptized, you can speak with your pastor about a conditional baptism, which you and chosen godparents may then witness.
If there is a sacramental record of the baptism, check with the orphanage to find out if the baby was given the full baptismal rite or just the sacrament itself. If the full baptismal rite was not done, speak with your pastor about “supplying the ceremonies,” during which the rest of the rite (minus the sacrament) is performed. Ordinarily, “supplying the ceremonies” occurs when a baby in danger of death has been given an emergency baptism and later recovers.
If the full baptismal rite was performed and a sacramental record was established, then you might ask a relative or friend to be a spiritual mentor to your child, and announce this selection at a (belated) reception given to honor the fact of the baby’s baptism. In time, your child might choose this mentor to be his confirmation sponsor.