are you keeping records of your efforts to make or encourage contact between the bio mom and child? do you ever take the measure of calling her residence and putting him on the phone to show you have tried to keep them in contact? do you allow him to write letters to his bio mom? if so, send them certified so she has to sign for them and you can prove she got them.
i know it seems like your the one who has to jump through all the hoops when your'e the one who has been towing the line and doing the right thing all along, but believe what the other poster said when the "dot all you i's and cross all your t's" comment was made. it's the truth.
i had to call my ex and put my daughter on the phone because he wouldn't call. i also timed the phone calls and kept doumentation of that and how often we called. i had to send letters certified; otherwise i knew he'd say he never got them. if or when he did show up, which was quite rare (about once every 3 months), i would document how long the visit lasted, etc. i realize it seems nit-picky, but in the end, keeping track of all these things on paper will benefit you in the long run. you can get up in court and say that bio mom didn't do this or that, but if you have taken the time to document it all and have paperwork to back up what you say, she'll be standing there empty handed looking like a fool.
that's just my two cents on the subject. good luck with your case.