Custody!

Okay so recently we’ve had my step son majority of the time, she’s only had him maybe 8 days a month the past few months but due to my SO hours being cut down and only working 3-4 days a week (normally worked 5-6 days) were really tight on money. I love having my step son around and it sure brightens my SO’s days being able to wake up with him here and see him all the time! They haven’t gone to court, never needed too! They just seen a mediator and set an amount to pay for child support and he’s ALWAYS paid, never missed a month since his son was 6 months old and now is 10 years old but he’s also not ever had him this much! Anyways, I was wondering if it would be wrong to ask to drop the child support even just a bit the months we have him majority of the time? Like I said, it’s not really court ordered payment amount or custody, they have pretty much figured it out on their own but my SO is fearful that she won’t allow him to come over if he mentions it! It wouldn’t even be a suggestion if we were financially well off but taking that we’re struggling and have him so much into consideration I personally don’t feel like it’s the worst idea, if I were in her shoes I definitely wouldnt expect to be paid in full if I didn’t have my child that often. TIA!