Surprinsingly enough, I think it would do well for Sakura's character to have Sarada being the byological mother.
Hear me out: With Sarada being Sakura's mother, everything she did for her daughter its just what a caring mother does for her offspring. But if she wasn't, all her care creates a much more powerfull effect and show the hearth of Sakura Haruno, who could be so assertive on Sarada seeing as she wasn't her daughter by blood. It shows true inconditional love.
Point is, I'm not pró SasuKarin, but I like the possibility that Karin was used as a surrogate mother (Sakura couldn't have babies on her own) and Sakura embraced Sarada as her own daughter and loved her inconditionally.
Plus those juicy Uzumaki genes
Hear me out: With Sarada being Sakura's mother, everything she did for her daughter its just what a caring mother does for her offspring. But if she wasn't, all her care creates a much more powerfull effect and show the hearth of Sakura Haruno, who could be so assertive on Sarada seeing as she wasn't her daughter by blood. It shows true inconditional love.
Point is, I'm not pró SasuKarin, but I like the possibility that Karin was used as a surrogate mother (Sakura couldn't have babies on her own) and Sakura embraced Sarada as her own daughter and loved her inconditionally.
Plus those juicy Uzumaki genes