While whatever CP's attorney is stating is what he will be saying to the judge...thats their case (all the things he has said); he is being pushy and while TX is a easy state for move-aways (according to what I have read here) he is still speaking a bit out of his bounds. Try to not take his words as legal gospel.
As for as your son's attorney, I would love to see imput here as to how TX deals with moveaway...costs of transportation to NCP. From reading post's on here, it seems other states are universally on the track that the moveaway parent must shoulder the majority, if not all, of the transportation costs. Especially as CP's attorney is suggesting that with mom and new hubby they will be the more stable...what?!...turn that one around and say if they are more stable, then shoulder the costs...all of them.
If someone here suggests the request that dad shoulder 50% is savvy in TX, thats one thing. If its not the protocol, I would seriously look at the lack of aggressiveness on your son's attorney's part. He needs an aggressive attorney who is capable of putting up the best case he can for the dad.
I truly think if an attorney dug into this, and came in hard with requests that mom will need to shoulder the majority of transportion costs, as well as the son spend the majority of summer in TX, as well as more of the school break periods than current...mom may wish to reconsider.
As well, but just my point of view vs legal opinion, given the long lengths of time children will be spending with one or the other parent...consider the AGE of the children in that. Look up TX visitation standard guidelines according to age and see what they say. It won't make or break dads' case, but is relevent and worthy of being added in.
I would look into where mom proposes to move in WI. Go ahead and look up exactly what types of plane fares are available. Is it one direct flight? Is it two flights? What does it all look like, traveling one way will take up a whole day? How much is the cost for two children traveling? what are the airlines policies on age/children needing the parent to be with them on the flight? How many years before they can fly alone? Add it all up, spell it out...is a once a month visit even feasible with the travel time, and not missing school? How much exactly will it cost for dad to drive to local airport, is a sleepover necessary? I would pretend its all happening and add it all up...the overall cost of each visit, then times it by whatever dad is requesting...and have his attorney put that out there.
(don't forget to throw in that Monday holidays should go to dad for once a month visits)
ANother point, if dad behind on child support, how can he be paying for flights? Of course perhaps that goes against him a bit, but perhaps not.
I would look into his attorney situation, and make sure he is an on top of it, and aggressive enough attorney. Sorry to be like that, but I'm just not sure about him.