When partner opens 1 or 1 and you have opening bid values, it is best to get into a 2/1 GF auction when possible. When the opening is 1, however, and you have 5+ spades, you can't suppress the suit; you have to start with 1 and catch up later.

What if you have opening bid values and support for partner? With 3-card support, start with a 2/1 in your longest suit. Your 2/1 response promises at least 4 cards. The auction 1-2 is the only 2/1 response which guarantees 5+ cards. Yes, you are stuck in the exact situation where partner opens 1 and you have a 3=4=3=3 GF. You will have to tell some lie (I prefer 2 on the 3-card suit). However, I like to play 1M-3NT as a balanced 13-15 (3 trumps and any 4-3-3 in the other suits), so that can often solve the 3=4=3=3 dilemma.

With 4-card support for partner I prefer to show it right away (either via a Jacoby 2NT or a Splinter-raise if in range). A Splinter-raise shows 4 trumps, 0-1 in the suit and about 12-15 in support. With more, don't use a Splinter bid (start with Jacoby 2NT).

Remember, that 2/1 GF is off in interference (if they double or overcall). It is also off (of course) if the responder is a passed hand.

You might also consider getting Larry's book on 2/1 Game Force HERE or try Michael's 2/1 Webinar series which you can find HERE.