Hmmmm, getting the precise details worked out up front eh
I think different factors play into this. Culture is obviously one of them so you're going to have to use those as guidelines also. Doubt you are living solo on a remote island. The children are going to have to interact with the rest of their 'world' in the future and the world can be cruel to children.
Also there's 'roles' involved depending on your arrangements. The biological facts may not end up matching the roles you all assume. For example, even though you might be a birth mother to a child, you might be a busy traveling professional and another woman might assume the 'role' of Mom. Same thing with configs with the men. Father and Daddy.
Whatever the situation, I think the children will make some decisions in this themselves. And it's certainly easy enough when the time comes to explain that they CHOOSE to call someone Mom or Pops (or whatever) based on the ROLES they fill - not the biology behind it.
And for some the Aunt/Uncle covers it all because nobody can argue that we're ALL brothers & sisters - right ??????????