8.5 yr old wets the bed nightly

I have 2 step sons ages 8.5 and 7 years old. My 8.5 year old still wets the bed nightly and has nightly (except for a brief 2 month period). His father and I used to put him into pull ups at night and made his responsible for disposing them.  We asked him if he was ready to stop using them and try to stay dry on his own he said yes and it was smooth sailing for a few months.  We noticed that the old habits started coming back little by little again and tried to back track and see if we could find a problem.  His mother had not had a steady visitation routine at the time but had started to see them the 1st 3 weekends of the month, it was after that that the break through wetting had started up again. We talked with the child and then his mother and found out that when he was there he was forced to wear pull up ( and other forms of cover ups) while he slept there even though the child was very vocal about not wanting to wear them.  We have tried to talk with his mother but has gotten us no where.  See insists that when hes with her he'll have to wear pull ups and thats final.  She has told us that washing all of the wet linens were to much of fuss (even though thats what we've been doing all along) and that it was easier to just throw away a wet pull up.  

We don't know what to do anymore.  He's a very shy child and is noticiably upset when he comes home and can't wait to tell me about it when he returns from his visitation.  Any suggestions?? We need help he will be in 4th grade next year and we are beginning to worry!

[cconchita]

Try taking him to a child therapist of psycologist.
They are very skilled at breaking through any psycological barriers that may be caused by the mother not trusting his ability.