Should I contest my late father's Will?

Question Details: My late father's Will states in the event my mother predeceases him, which she did, he gives, devises and bequeaths all of his estate to his beloved daughters then names the 4 of us. One of the daughters named is a stepdaughter. She only lived in my father's/our home for 6 years from age 12 to age 18. Adoption was never discussed and she never went by my father's name. As a married adult she contacted her absentee biological father and formed a relationship with him and his 2 sons and their mother. She was named as an heir in his will, but not in her step-mother's will. I am certain the attorney preparing my mother and father's wills was not aware that one daughter was a step-daughter. Their Wills are identical with the exception of the change of names and relationships where appropriate (i.e., beloved wife to beloved husband, Jean to Donald, she to he, etc.). Since the attorney was not aware of the situation, she did not have the opportunity to explain to my father that his will did not have to be identical to my mother's and that he had options. My mother's mindset was always we have four daughters or 4 girls. They went to have their will made and did not realized it would actually be 2 separate documents - 1 in each of their names. My father never realized that his Will could have been different from my mother's by leaving his estate to his 3 biological daughters. Since my stepsister is listed by name as a daughter, is there any grounds to contest the Will?

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