How do I text forward from two iPhones with different Apple ID

only way is to disable imessage 100% on both devices settings->Messages

better solution is to not use the same appleID and just use family sharing between the 2 appleId's

otherwise you also can't facetime between the 2 devices and you share a call log which can't be changed

Continuity features only work between devices signed into iCloud with the same AppleID.

Hi. I don't think you can. Continuity, including text forwarding, only works between devices logged in with the same Apple ID.