Primary residence of the child is changed

Wow! The TX Legislature has made some big changes this time! Now if the parties agree, there is no need for one of the parents to be designed as "the parent with the exclusive right to designate the child's primary residence". Now the legal documents only need to include what the geographical area will be for the minor child. Again, as attorneys wrestle with this new change, it is going to be interesting. Many parents agree that the children will live within Harris County and any county contiguous to Harris County (such as Galveston, Brazoria, Montgomery, etc.) So there are several school districts involved. One possible solution will be to restrict the child's residence to certain school districts. In theory, this is a very positive solution. However, I'm curious to see how people that have not been getting along are going to "cooperate". What will school districts do? It's unknown. Can Dad sign the kid up in Ft. Bend School District and Mom sign up the kid to attend HISD?