Divorced dads do you pay extra for things that should be covered under child support?

What i mean is if you pay the max the court ordered(child support,daycare,and medical expensives) plus have joint custody 50% do u pay for extra things like sports fees,toys/clothes for your ex's house ect?My husbands ex will have thier son call and ask his dad to pay for these things and he allways does.Now money is very tight for us and his ex is not hard up.Now i'm not an evil stepmom(i love my stepson) and my hus is not a dead beat dad i just feel these things should come from the child support money my hus is allready paying her.i feel his ex is taking advantage of my husbands love for his son as this happens often.Should i just let this go?I have tryed to talk to him about it but he just get defensive.