AL78, on 2023-December-02, 15:30, said:
This is not really a 2/1 issue (or even a 5-card major issue) - in all natural systems you need some way to show a forcing raise, and it doesn't make much sense to play 4♣ and 4♦ as splinters if they are the only forcing raises available. You don't always have a singleton.
You could of course agree that this specific hand starts with 2♣ or 2NT or whatever, but you also have to have a way to show a strong 53(32). Or maybe those hands start with 2♠?
On the other hand, I am not sure if 4♣ and 4♦ as control bids are that great. It doesn't help opener to evaluate their hand if 4♣ could be a void or a stiff or a king or an ace.
In Nightmare, 3♥ is forcing and that's maybe not such a bad idea. Otherwise, what about 3♣ or even 2NT as a generic forcing bid after the 2♥ rebid? You don't have a GF 5125 that often, 3♣ should cover more hand types than that.