IF you have a high enough relation or some ridiculously amount of charm you can convince a house ( by talking to it's head ) and trying to convert them to your side, mainly by ♥♥♥♥-talking about they're current liege. Good luck on this as getting high relations may be hard, charm is near enough impossible. Is they're is a charm cheat?!
fixed. male companions cannot marry other ladies, and neither can any other vassal in the game. male companions cannot marry female companions. the only option they have for marriage is the player character. and that's not what's being asked. so no. What was asked by OP: "Can my companions, after they became lords marry the maidns of the relams