Problems with step parent

[cowgirlup]

My husband's ex-wife recently remarried and both of his kids HATE him.  He has a tendancy to pick on his son who just turned 12.  If he doesnt eat everything that is put on his plate, even though his mom knows he doesnt like it, he is grounded.  The step parent didnt even ground his own daughter when she didnt finish her food.  I can't tell you how many times he has been grounded for this.  I understand that the child needs to do as he is told but when the step parent doesnt like the child and treats him like crap what do you do?  The question is, if the son wants to come live with his dad and step mom and the dad is a truck driver that is only home on the weekends, how difficult would that be?  Could he still get custody of his son in those circumstances?  I work full time and my son (his step brother) lives here also and goes to school too.  Would a judge allow the dad custody if the son would be with his step mom all week?  My husband is ready to go over there and throw down on this guy.  The step dad has already told my husband that they dont have to get along and that he should not put his nose into their business, but my husband feels that because his son is being "targeted" by him, and it is his son, he has every right to make sure his son is being treated with respect.  Does anyone have an answer?