In reality you do not need to involve her.
In any Family Tree you can assign Relationships as you want from a selected list.
What this means is for an individual in a tree you can have more than two parental relationships set, i.e. Step, Biological, Adopted etc so you have Two Father’s shown in your tree, one Biological and the other Step or “Adopted”.
Then you have tree branches from each going back through their lineage and with the person with Two Father’s which line you want to view in the Family Tree is selectable. In a Family Tree on Ancestry view the person and click of Edit Relationships and select Make Preferred