It would require her signature IF SHE IS ON TITLE of home.
Have an agent also search MLS records if home sold thru an agent listing agreement would require all owners of home sign listing agreement IF HER NAME is on title.
If her name IS NOT ON TITLE, her former husband can do anything with property as long as no other court documents have been signed.
CONFER with an attorney after you have completed your investigation. Title company who transferred title is held responsible for all parties signing.
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