In this heirship dispute between the decedent’s alleged common law wife and the decedent’s biological daughter, the sole issue we consider is whether the daughter conclusively proved that a petition for bill of review filed by the alleged common law wife was precluded under the doctrine of res judicata. The probate court granted a motion for summary judgment in favor of the daughter upon concluding that the petition was so precluded. We disagree with the probate court and conclude that the daughter failed to prove her res judicata defense as a matter of law. We accordingly reverse the probate court’s summary judgment and remand the case to that court for additional proceedings.