Divorce Support Forums: What is best for the child?

How does Oklahoma look at child support reduction and visitation? My husband's son lives in Europe with his mother and stepfather. In the mediation agreement allowing her to take him overseas she agreed to bring him back to the USA at her expense, pay for health care, and have my stepson call every other week. None of this has taken place in the seven years he has lived over there. My husband either pays for him to come here or he goes over there. My dh calls twice a month. This child has not lived with my husband since he was 20 months old. She complains that $400 a month is not enough and sends us very hateful and threatening emails. the ex tells us that her husband is more of a father to their son than my husband. To make a long story short, the relationship between my husband and his son is very strained. The visits are difficult at best. Is it fair to bring the child to the USA to visit when he would rather stay at home? (He hates the fact that my husband is in the US military.) He sulks the whole time he is here. But, my husband says his son is very distant when he goes over there to see him. What is best? Just continue the calls and ease up on the one year visitation? Try to push for more visitation? He is in school 10 months out of the year. How do you know what to do in a situation like this? Any suggestions would be appreciated.