Mac account link to new user ID

My iMac (Big Sur) has always been linked to my wife's Apple ID. The administrator log in is linked to her devices -iPad, iPhone. It's there where all of our family data is kept, photos, videos, documents etc.

A few years back I created another account on the Mac specifically for things like music recording. It's also where I primarily surf from. Last Christmas I got an iPad, and set up my own user ID. I've never used messages from the iMac, so I wanted to set it up so I could text my wife from the Mac to her iPhone. It prompted me to sign in, so I did from MY apple user ID. However, I see all of her texts and messages so the Mac is somehow still linked to her Apple ID. Is there anyway around this? Do I need to create another Mac account linked to my new Apple ID?