Sec. 6. (a) This section applies:
(1) when an agent of a decedent testifies on behalf of an executor, administrator, or heirs concerning any transaction the agent had:
(A) with a party to the suit, or the party's assignor or grantor; and
(B) in the absence of the decedent; or
(2) if any witness testifies on behalf of the executor, administrator, or heirs, to any conversation or admission of a party to the suit, or the party's assignor or grantor, made in the absence of the deceased.
(b) The party against whom the evidence is adduced, or the party's assignor or grantor, is competent to testify concerning the matters described in subsection (a).