Weird account issue with gamecenter

So I play swgoh on iPad. My account has always been linked to both a gamecenter account and an ea account. The ea account it’s linked to is mine, the gamecenter account that it’s linked to is not. The gamecenter account is owned by my father. This is kind of a relic of the past because when I started playing like 8 years ago I was under his account because I was much younger. Anyways fast forward to today my father wants to start playing swgoh randomly. Well my account is linked to his gamecenter so when he installs the app on his phone he is immediately signed into my account, and there’s no way for him to sign out  because gamecenter accounts override ea accounts apparently. He tried signing in with his ea account but it said his ea account birthday and my swgoh account birthday didn’t match (well duh). So I decided to sign out of gamecenter on the iPad that I play on because I knew I could sign in with my ea account still once gamecenter was unlinked from my account. Well I go to sign in with my personal gamecenter account and try to link it to my swgoh account and it throws me an error. Every time I launch the app I have to sign in with ea again, when I do it recognizes my swgoh account and asks me to select if that’s the correct account. When I select it every time it tells me there’s an error and to restart the game or contact support. Error code 9 if you need it.