questions on komon

A freind of mine is wondering...

... a few question about the Ka-Mon
(Japanese family crest). I wanted to know how the inheritance of the
Ka-mon is carried out. For instance, when people get married whose
crest do they take, the bride or groom? Are all the children in the
family entitled to it? And, did inheritance guidelines change over
time for the crest, for instance, at one point only first born boys
were entitled to inheritance?

Can anybody help her???

thanx a lot
cepo