Since she asked if ex had water, I was wondering if she might have stopped somewhere to GET SOME WATER (kids need water) and may have been hijacked or abducted by someone where she stopped, taken somewhere, forced out of the car near the water tower where her phone pinged (along with her phone) and the abductors high tailed it out of there. Finally, they may have parked that car somewhere else later and the two who were temporarily detained found car (with keys in ignition), stole it and parked it at the Motel 6. It would be so interesting to know where the two who were running away and apprehended found the car originally.
All this is just supposition (MOO) and not even an opinion, actually. I feel sure the ex has told LE a LOT more than we are aware of. There were probably verbal conversations, and she may have mentioned stopping for water, etc. She was a beautiful woman, driving an expensive car and all alone. With all the chaos in the area, anything could have happened. I don't want to believe the ex or her bf harmed her.
Praying she is found soon.
JMO