There is no orchestra. Emily doesn’t like Sarah and has no interest in being friends with her. I don’t see why that other lady can’t be friends with Sarah and Emily separately.

Orchestra analogy would be appropriate if this was group situation with everyone attached to the hip. Typically adults can have separate friendships with different people.

They don’t have to all play in The same orchestra. Perhaps that lady in question and Sarah are closer friends/best friends etc hence they appear to like each other more. But it doesn’t mean they can’t have other friends separate from each other