Hard to know for sure, since you had so little contact with her.
It could be that you're invited to make up the numbers. The sister wants a bigger party than her social circle allows. Or they have way too much clam and need to draft in some extra sausage.
It could be that you're invited to make up the numbers. The sister wants a bigger party than her social circle allows. Or they have way too much clam and need to draft in some extra sausage.