Raising child support after an adoption

[Maggie15]

My husband has a child from a previous marriage who he has been paying child support plus additional expenses faithfully & on time for the last 8 years. We have a new baby at home and are in the middle of a foreign adoption and his ex-wife wants to raise child support because he won't pay for braces. In the modified agreement there is a clause states they must agree on additional expenses. He did not agree and she did it anyway/ She is now angry because we are not paying and taking us back to court for additional support. My husband carries dental on his son that is not required by the court order. That coverage is pay $1k towards the braces. Now that we have children in our home will she be able to increase his support? He has had a raise net of about 10k. I was thinking that would be offset by the additional child/children? We live in Florida.