How do I connect my origin to EA play?

So my dad originally started an Origin account yeaaaars ago when I was young which I used to play sims, now 10+ years later we have to move to EA play, but I can’t connect to EA play because my dad never had an EA account (as far as he can remember?) and can’t remember which email he used to set up origin..

(I only know the username and password but not the email address which is how i always accessed the origin app) 

how am I supposed to move my origin games over to EA play when I can’t even log in to EA .. and I can’t just start over, I’ve spent so much money buying all the sims games over the years on origin. 😥

I have my own EA account but that wasn’t what was used for origin.. is there maybe a way to transfer stuff from his origin to my EA?

And now I’m stuck not being able to play because you can’t access origin anymore..?! Someone please help!