porting phone number from dad tmobile account to my new account

My dad’s tmobile account is separate from my new account. He will cancel his entire tmobile account. What he want to do is release one phone number before he cancel so I can port those number into my own account. Would this affect my own existing promotional account? I’m on the Magenta Max 55+ and his account is under TMO ONE All In Promo (older promotion). 

So what would be the proper procedures to do this number port without affecting my own promotions. His doesn’t matter since he will cancel his own account.

Am I providing clarity for my situation or is it more confusing? Thanks all in advanced.