You need to talk to someone who is familiar with the law in the state where the timeshare is located, as there are quirks between various states. Note that some of the advice in this thread has limitations like ''in most states''.
For example, the North Carolina legislature years ago passed a law, which is still on the books, that abolished joint tenancy in the state. However, some years later, the state Supreme Court rendered a decision that essentially said that in spite of that statute a joint tenancy could still be created in the state if you did it a very specific way. On the rare occaisions that North Carolina lawyers create joint tenancies, they usually track the exact language approved in that case, as otherwise the vailidity of the joint tenancy is highly questionable. On the other hand, tenancy by the entirety has always been recognized in NC, and is very simple to create, by the inclusion of two words in the deed.
I have seen many deeds prepared by the out of state timeshare closing companies which use laymen in another state rather than an attorney in North Carolina to prepare deeds screw this issue up by recording deeds using joint tenancy language that does not follow the state Supreme Court's language. Instead they use something that may work fine in their own state but does not pass muster in NC. This screwup means that the buyers end up with a tenancy in common rather than the joint tenancy they wanted, which could be worse. There are other common mistakes that these closing companies make regularly which mean that the buyer ends up with an invalid deed that does not convey any valid title at all.