Family Historian User Group

I have a 71 year old cousin who just found out (via DNA testing) that her "father" (deceased) was not her biological father. Her biological mother is also dead, so she cannot find out who her biological father was.

I am trying to find a way to disconnect her from her non-biological father, but keep her connected to her biological mother. I suppose I could create a new Record ID for an unknown spouse/partner for her mother, and then connect her to that unknown person.

Is there an easier way that would not require me to create a Record ID for an unknown person?

In the Focus window for your cousin, right click on the father and select the "Unlink Record" option.

Then go to the Property box for the mother and click on the second family tab and add the child back in there using add existing record.

I would not unlink your cousin from her 'step' father, because presumably he raised her as his daughter, just like a foster or adoptive parent. Family history is not just about blood-line genealogy. It is perfectly feasible to have more than one set of parents.

What I suggest is you set the Relationship to parent:-
In the Focus Window with her Father in Focus and your cousin as a Child, right-click her Rel. box on the right, and choose Relationship to Parents > More Options.
Tick the Specify relationship to each parent separately option.
Then for Relationship to Father choose Step.
If you wish you can set Relationship to Mother as Birth but that is the assumed default.

In addition, if you wish, you can create another family group with or without a biological father.
In your Cousin's Mother's Property Box, on the blank Spouse tab, you can Add Child > Link Existing Record and choose your cousin.
Optionally you can Add Spouse/Partner > Create New Record and whatever limited details you know, such as Status: Never Married.
Finally use the black arrows to the right to move this new tab to left of existing tab.

Thank you for the suggestions. By using a little bit of what everyone suggested, I created a configuration which is biologically accurate, but also documents how her non-biological father was the familial "father" who raised her from birth.

My cousin also had a brother (actually half-brother, since the DNA results were released) who was a biological son of the non-biological father of my cousin. So, I had to keep the non-biological father in the family tree since he was the biological father of my other cousin.

So, the resulting tree now shows my cousin's biological mother with 2 children, by 2 different men, one of whom is unknown. By adding some text in my cousin's Birth Notes, I am able to explain how she had both a biological & non-biological father. Probably sounds confusing, but it does now present an accurate depiction of what occurred.