Can we make an adoption contract with the birth mother?

We are working with an adoption agency in Oklahoma City and they have located an infant for us to potentially adopt. The birth mother says she will not consent to the adoption unless she has a written agreement from us that we will allow her some contact with the baby after the adoption is finalized. She would like a couple of visits each year and possibly more as the child gets older. She also wants us to provide her with updates on the child, including things like school report cards and photographs. We are not completely opposed to this but we don’t know what the Oklahoma law says about this type of an agreement. Are we legally able to enter into a visitation type of contract with the birth mother? If we are, what should be included in the contract?