No, they are not related to her and can marry her! Only the step father is her Mahram.

Is stepfather’s brothers&father are maharem for stepdaugher?

Mahram | August 9, 2015 8:11 pm
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If i go to an invitation where every male is mahram to me,but not mahram to other women invited there.however, i have to accompany free mixing.is it allowed to go there
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My father and step mother are divorced, is she still my mahram?