im already study both hapido and tkd here at uni. the hapkido class is fairly new and the instructor (Master Kim Beom, 7thdan hapkido, 5th dan tkd) told everyone when we started kicking that we would learn to kick the hapkido way because it was a hapkido class, he didnt care if we were tkd or kung fu or karate. it is pretty dodgy for someone to tell you you have to learn another different martial art before he will teach you his. hapkido does rock tho, you should definately take it up