I would stipulate in a custody agreement about sports and other activities.
When we did Boy Scouts, we had more than one father that had to take and ex to court about this. It was not a case that the kids had too much going on but the mom's did not want to bother with an activity they did not choose. Or "gasp" they had to let the child with dad on an unassigned night like Tuesday.
In our Girl Scout troop there is a dad that has to either take the girl to Girl Scout functions on his weekends (doesn't happen often), allow mom another adult, or he is in contempt of court and could lose visitation. BUT!! The mom has to give him at least one-week notice with proof that there is a function (she was busted using fake Girl Scout events to interfere with his visitation
). It is stipulated that summers be dived between the summer camp/s she chooses. Neither parent can figure out why she chooses so many camps and can't wait to do month long ones.
My son had a kid whose parents went to court over swim team and weekend obligations.
These are families that live close and mileage does not create a problem. Within reason, a child should not miss activities because his parents live apart. On EOW, the custodial parent should take the child or allow the other parent to take them. Both parents should be able to have input on activities and how many. One Boy Scout's dad struggled because his ex-wife put the child in so many things that Boy Scout was interference. Judge did not appreciate when the child's lawyer (court appointed advocate) stated that mom was abusing privilege that the child only wanted to do Boy Scouts with his dad and 1 other activity with his mom (forgot which one). That the child did not like all the activities his mom signed him up for and the mom was not taking the child's feelings in to account.
With ALL these cases, it was more about what the kids wanted. The parents had to let their kids participate in activities even if it unconvinced them. This was both parents inconvienance not just one parent.
I would set up a EOW schedule, make sure she knows the schedule to what ever activity. Then she can work around that.