EWTN.com - Baptismal sponsorship: "Baptismal sponsorship
Is there a rule that you can sponsor a child with in a family only one time?
My husband and I are my niece’s first born sponsor of baptism. She recently had her second child and we have heard through the grape-vine of my family that she and her husband want to ask us to be their second child’s sponsor for baptism as well.
Answer by Fr. Jay Toborowsky on 10/28/2008:
There is no limit as to how many times a person may act as a Sponsor. The only restriction Canon Law offers is that a parent cannot serve as sponsor of their child."