My question involves name change laws in the State of: Missouri.

In the child support and custody paperwork, my ex is requesting that our son's last name be changed to his because it is in "the child's best interest". I have a child from a previous relationship with my last name, so I wanted both of my kids to have the same last name. I am not against hyphenating the last name, though (although that's not what he requested), but I don't feel I should have to - my son's dad was never a good father and is just doing all of this to be spiteful. If he was a great dad, the situation would be different and I would want my son to have part of his name.

What are the odds of a judge actually granting his request?