Self esteem and parental behavior

I have some friends that have been divorced for 10 years now. Mom has had custody until about a year ago. The main reason for the divorce was Dad's alcoholism and subsequent physical abuse. Although Mom rarely received finanacial support, the only time she interferred with Dad's visitation was when he showed signs of being under the influence when he came to pick up their daughter. Under these circumstances she refused to let her daughter leave with him, and rightfully so. He never accepted that, and held a grudge about her always "calling the shots" where their daughter was concerned. Dad never really wanted to be a full time father until about a year ago when he was diagnosed with a terminal illness and placed on disability. Money got tight and he found out his disability payments would increase significantly if he had custody of his daughter. Mom had been in a car accident and was recovering slowly. They went to court, and the judge (in his infinate wisdom) granted custody to Dad so that he could spend some "quality time" with his daughter before he died (since mom was somewhat incapacitated from the wreck anyway). Ever since they got custody both Dad and step mom have continually critisized and demeaned Mom, and they have made it difficult at best for her to exercise her visitation rights. They would tell the daughter that the scheduled pick up or call time was much earlier than it was, and then do such petty things as taking the phone off the hook or leave the house right before she was due to pick her daughter up. They would then tell her daughter that if Mom didn't care enough to be on time, they shouldn't have to wait on her. Although her Mom explains, she's always left on the defensive. Mom's trying to get up enough funds to return to court, but money's tight. I have tried to tell Dad and step-mom that their negative attitude and selfish antics are hurting their daughter more than their hurting her mom. I know there must be some good reference books for foster parents that speak to the subject of how a child's self esteem could be negatively affected by behavior like this. If someone could give me the names of books or articles I can give to Dad and Step-mom to substantiate that position I would really appreciate it. I feel like I am watching a flower wilt the way her daughter is changing since the move. Thanks, Trish