The proper place to get accurate advice on this subject is from an attorney who specializes in estates and trusts.
Generally, there are two ways to ensure a pretty simple transfer to your heirs.
One way is to enter into joint ownership with your heirs. Properly titled, in the event of the death of one of the owners, the other owners still have uninterrupted ownership -- without probate. (You can also pass ownership through your will, but wills have to be probated which is a lengthy and costly process.)
DVC Member Administration can help you with converting to joint ownership. However, as others have mentioned above, joint ownership has some drawbacks as well...especially if one of the owners gets involved in financial difficulties, divorce, etc. Joint ownership is just like a partnership in the sense that one partner's problems can become everyone's problems.
The other method is the use of a trust. A trust would also avoid probate and could insulate you from liabilities caused by one owner's problems. Usually, trusts are used as a part of a much larger estate management strategy, rather than only for one small asset like a DVC ownership. You'd really need to discuss your overall financial situation with an attorney specializing in these matters to get good adivce, because trusts are very technical. (Our DVC account is held in a family trust, and it fits very well into the larger picture, but a trust would not be the best alternative for every family.)