I'm not sure that I understand what you mean. Do you want to add information about an existing character to another's character bio, or do you want to add more characters into one bio?

If you want to add information about another character into an existing bio (as so long as it fits in with the bio), that's fine. But as for adding multiple characters into one bio, that's not allowed.

that's not what I meant, (on having two character's on the same character page), I meant remove one of your character, then added that character's history and parents, on another character's page,

if you mean have one page for two characters then no - while the case for some offical characters - all characters must have there own page.