I have a daughter. (20yo)
My husband a son. (16yo)
We have a son. (12yo)
We have a daughter, (5yo) who is the bio-child of my boyfriend and I.
We all know this.
We've raised/are raising all of the kids together as a family.
(the three of us live together and have for nearly 10 years).
Honestly, I think it doesn't matter how you do it as long as all of the adults are on board with how you do it.
Kids just need love-they don't really mind if it's more than two people!
"Love As Thou Wilt"