Multiple accounts Facebook/Instagram

Good afternoon, I have a new job and am responsible for the social media and marketing area. I opened a new work account on Instagram and Facebook connected with my private ones but there are others connected with my boss. He gave me the admin rights for them but now I can’t figure out how to connect the ones I made because Facebook of course wants to get connected with my private Instagram account and creator studio isn’t really helpful yet. I m so confused….
Hopefully someone can help?
Thanks in advance