iPhone 6 is going to be unsupported - switch number to existing iPhone SE 2nd generation?

My 96 year old father recently passed away, and support for my iPhone 6 via Xfinity Mobile is likewise scheduled to pass away in September.

I now have my father's iPhone SE 2nd generation (that I got him to buy because he too was all Comcast and could get Xfinity Mobile) and am wondering if I can bring his phone number onto our plan, but swap phone numbers between my 6 and his SE so in September my cell phone number doesn't die.

(With the phones switched I'd have time to get my stuff off my iPhone 6 and onto the SE. (His stuff is minimal, so not much to save...)

Has anyone done similar before?

thx