Pennsylvania Petition to MODIFY CUSTODY is a legal filing used to request a change to a current court-ordered custody arrangement. It can be used to modify a physical custody order (where the child physically resides), a legal custody order (which grants one or both parents decision-making authority over the child), or both. In Pennsylvania, there are two primary types of Petition to Modify Custody: Agreement to Modify Custody and Petition to Modify Custody. Agreement to Modify Custody is a type of petition used when both parents agree on the proposed changes and have signed the Agreement to Modify Custody. Petition to Modify Custody is a type of petition used when one parent is requesting a change in the custody order and the other parent does not agree to the proposed changes.