Tennessee Code Title 66. Property § 66-1-112

(a) A transfer of a possibility of reverter or right of entry by a holder other than the original grantor is invalid; provided, holders of a possibility of reverter or right of entry may freely transfer the interests to the holders of the corresponding fee simple determinable or fee simple subject to condition subsequent for the purpose of merger of the interests in any grantee.

(b) This section applies to future interests regardless of whether the interests were created before, on, or after July 1, 2015; provided, this section does not apply to any future interest, the validity of which has been determined by a final judgment in a judicial proceeding or by a settlement among interested persons prior to July 1, 2015.