zeebee1 said:
Konoka's past made it clear that prior to Setsuna she didn't have any friends. I'm pretty sure Motoko stayed away.
No friends just means that Motoko didn't play with her. After all, there was probably at least ten years between them. I know that most teens don't want to associate much with their younger cousins, especially if they're younger than ten, as Konoka looked to be.
Also, Motoko and her sister 'did' visit the Konoe family at least once, when they dropped off Setsuna. That was confirmed by Akamatsu.