I am also trying to design such a system. However, my question is how can you find a 4-4 fit in the other major if the opener has a minimum hand and the responder has a potential slammish hand with 4 card in other major and 5♣. e.g. 1♠ 2♣ 2♦ 2♥ (assuming it shows a balanced GF raise in ♠) what if the responder has 5 ♣ and 4 ♥ GF and the opener has 5♠ and 4 ♥ and minimum? Similarly for 1♥ 2♣ how can we find a 4-4 ♠ fit with responder having 5 ♣+4 ♠ and the opener having 4♠+5♥ minimum?