Need some advice

My husband pays child support for his kids - $1050 a month. He does get bonuses throughout the year - and the way the agreement is - is that he pays the top up in June. So basically whatever the difference is - he pays that in a lump sum. This year it’s about $7500. On top of the 1050 we pay monthly. She also gets about $2200 baby bonus from her three kids (she had a third last year) and hasn’t gone after that dad for any support. She is very bad with money and basically uses all the money we give her - for herself. My husband and myself are trying to figure out if it’s worth it to get a lawyer to try to mediate things. We have no problem paying child support - but we are wondering if we can set up an extra account for them - and the top up in June goes to that account. That way we know the top up is going to our kids and not up their mother’s nose or on the vacations she loves to take.

Just curious if anyone has any experience in this !!