So you guys were right. I reserved an ATT 7 plus and tried to do t mobile IUP. No go. However, I am trying to work some magic. Lol
What I did was buy the phone full price. I then called t mobile and had them add the IMEI to their network. Then I'm going to attempt to return the phone and buy it immediately again with t mobile IUP. T mobile did add it without issue.
I need all the good vibes and luck I can get from everyone lol.
edit: added a screen shot from tmo help. I'm still not sure this will work but I'm a least a little hopeful at this point.
I'm also going to keep checking for t mobile plus devices online during this time because i could just return this ATT one and do IUP with the t mo one.
Sigh the things I do to give apple my money lol