Also Law won't join Cross Guild, he doesn't fit the Yonko Commander line up like the others Yonko crews
Buggy = “Captain”
Mihawk = “YC1” = 3.6 bil
Law = “YC2” = 3 bil
Crocodile = “YC3” = 1.9 bil
And if Law and others join cross guild, Buggy will definitely get a bounty boost to be above Mihawk