Can father pay for maintenance of child in one time ?

Consider the scenario: Spouses have taken divorce by mutual consent. Husband has paid all future maintenance for wife and one minor child as one time settlement amount. Wife has given up all her claims, past, present and future in consideration of the settlement amount. Also she has given up all such claims on behalf of the minor child as well. Custody of the child remains with mother, father having visitation rights. 1. Now, is it a valid legal proposition for a child to file maintenance claim from father through any legal guardian other than mother on the ground that his mother deserted him and he has not received any amount or maintenance out of the settlement amount. 2. And is father bound to pay this maintenance to the minor child even after he has paid one time settlement amount that included future maintenance of child as well? 3. What is the remedy to avoid such situation? Please guide. Regards