Tell the child no, he/she can only participate in non-weekend activities.
Allow the child to participate, but only on the weekends he/she will be with the local parent.
Allow the child to participate, but disrupt the custody schedule and leave the child with the local parent for the duration of the season and makeup missed weekends with the other parent after the season.
Allow the child to participate and whichever parents has custody should ensure the child get to their activity.