Bridge & other card games/Interference Over a 1NT Overcall
Are systems on for the advancer following a
1 NT overcall?
A big change the last several decades has come in responding to notrump overcalls. In the old days, cue-bidding the opponent's suit was used as Stayman. Nowadays, an easier (and better) system is employed. Simply treat a notrump overcall the same way as a notrump opening. So, 2C is Stayman, 2D is a transfer to hearts, etc. Pretend the auction started with 1NT. This is often called "Systems On" or "Front Of Card."
For interference, a simple suggestion is that if RHO bids over Partnerís 1NT overcall, then you just use exactly the same methods as if Partner had opened 1NT. So, for example, if you play Lebensohl, that would also apply here.
The above methods, however, are common but are not the only treatments available and are definitely subject to partnership agreement.