Answer:
dreads can be attached to existing dreads a few ways,
one is to comb out the matching ends a inch or 2, then mash the ends together and use a crochet hook to weave them together. (i would never use a crochet hook on dreads for any other purpose)
another way is the same except no crochet, instead put a bead or wrap over the joint to hold it while they dread together naturally.