The usual precedent for women is to adopt the husband's tartan as well as his name when married. While this is the direct opposite of your situation, it may be some inspiration for you.
Additionally, clans were not originally made of only direct blood descendants of the chieftain. Even today, centuries later, this is still the case. Clan members were those who fell under the authority of the chieftain and clan, and those who pledged their loyalty in peace and war to the clan. By pledging their loyalty, they became a brother to the chieftain, part of his extended family.
Adopting her tartan is a nice show for your inlaws, but select whichever of the thousands you like best and feel most comfortable.