You’re bang on. I guess the point I’m trying to make is why cross two S2’s separately, and then cross the resulting offspring if those S2’s are homogenous? In that case, you’d just take the F1 offspring from a single S2 cross and make your F2’s.
Idk, situation as described (I’m imagining sister S2’s unique enough to work separate lines) would result in F1’s. If the sister S2’s are relatively homogenous I’d be calling them F2’s too.
By no means is this 100% the right answer this is actually a great debate