Not sure how to handle

For context, my husband (42) and myself (36) have been married for 10 years. Up until last year, we had minimal contact with his son (16), but he has always paid quite a large amount in child support which I have never really questioned or pushed back on. Last year, we had the opportunity to be more present in his son's life, and we took the opportunity. From multiple flights, baseball games, trips, sport equipment he wanted, new clothes, etc., that first year we spent quite a bit on top of our child support obligations and because I knew how much it meant to my husband to be back in his son's life, I didn't really say much. At the end of the year, I did sit down with my husband and discuss the dollar amount and asked if we could go into 2026 with more of a budget so that we can still do fun things, but within reason. We both agreed on a dollar amount for beyond child support payment expenses. Fast forward to now, his son is now planning to live with us for a third of the year to pursue his sport more competatively as there are a lot more opportunities here. I personally think that is great and am happy to have him in our home. I am not ok with the fact that my husband is refusing to go to the courts and change his child support agreement. If he's staying with us for 1/3 of a calendar year, I don't think it's ridiculous to ask for a reduction. We're paying almost 100% of the costs for his sports, all of his living expenses while he's with us, plus $1500/month in child support to his mom. Am I out of line for saying that renegotiating that has to be part of this deal? I want to support my husband and have his son in our life, but financially this is killing my peace of mind. I do love my stepson, but at some point I just can't keep looking past everything and not build resentment. I hate saying that, but it's unfortunately true.