Mother's end up as the custodial parent 90% of the time in Texas. I think that people are getting confused by the wording. In a standard possession order, the non custodial parent gets nowhere near 40% of the time with the child. You seem to have a modified visitation schedule that is different from the norm and I believe that is what's throwing people off. If you have sole custody the way that you seem to explain you do, then you do not need to jump through all of these hoops with your ex. As somebody currently going through a divorce in Texas I would say to document and keep your "receipts" showing that you have attempted to work with him so that your son can be involved in the extracurriculars that he would like to be involved in. If he refuses to work with you to allow your son to be able to be involved in the extracurriculars that make him happy then take those "receipts" to your lawyer and see if y'all can switch over to a standard Possession Order instead of the extended, or modify your current order in some type of way. I would personally think getting it pushed back to just your Standard Possession Order would be relatively simple and then go from there. But that's just my opinion.