Kara Zor-El = The original Supergirl, cousin of Superman and survivor of Argo city. Not confusing.
My thinking is you have a Supergirl that is honest to the original or is the original or don't have one at all. Batman isn't weaker as a character because he has 15 junior batmen running around..how is superman? Is Kara his dad? his mom? He was a baby when he left krypton..He knows no one..his alienation and loneliness is still there. if kara is another loner then they are strictly 2 loners with a shared history and maybe a familial relation...it would still be lonely as hell and having someone around his junior would let him be a father or brother figure that he will inevitably become...
Your opinion that Superman is weakened as a character if he isn't the lone Kryptonian doesn't make any sense. He is still basically alone as far as having relations with kryptonians goes.... but he is so close to us as humans he isn't lacking in friendly and amorous relations. He has a surrogate family which Kara would sort of be an extension of she would be a stranger as much as anyone else. When another Martian popped up it didn't weaken Jonn Jonnz' character.... it just added new angles and story possibilities....
Does it make you cry because Supes is lonely? Hell no it doesn't so what emotional benefit is there to having him be the sole survivor of a dead planet other than your nitpicking? None.
Now Martian Manhunter should be considered lonely..he looks nothing like a human...he has green skin and has a bizarre appearance in even humanoid form...
Superman walks around like everyone else because he is human... having one or 2 more kryptonians just makes more story possibilities..he still comes froma dead planet where 99.9999 percent of the population is dead.
