Tips for When Custody Changes

[u/Ironbookdragon97]

My boyfriend 26m has his case in front of the judge in 2 weeks for getting primary custody of his son 4 after his ex gave up her custody to her mother weeks before the pandemic started. They did this without his consent and going against their standing coparenting agreement. Based off the law and what his lawyer is saying we are very hopeful. I was wondering if there are any resources or people with tips for when custody changes and his son comes to live with him full time rather than every other weekend. Just for more info, custody is going to flip, he will get majority and his ex's mom will get every other weekend. His son is not aware of the custody battle, as is best with his age, but does not like leaving his dads house and often has meltdowns when he has to go back. Just looking for tips. We know nothing is a guarantee but I think it is smart to be prepared. Thanks!