Research problems in genealogy are known as "brick walls." I have several brick walls, but the one that gets my goat the most is the Allen family. You may have gathered this from previous posts.
A new approach
I need to find valid and verifiable documentation of the parentage of Robert Scott Allen. I looked at my DNA matches and tried to find a descendant of Robert. Nada.
So I went into the Ancestry search feature and typed in the names of Robert Allen's children, hoping to find another family tree that had living descendants. The most fruitful search seemed to be Sarah Hilen Allen, who married George Wilson (for some reason there are many Wilsons among my DNA matches). I contacted someone who had these people in their tree.
She wrote back that Sarah was her 3rd great aunt (Sarah would be my 2nd great aunt), but that our DNA does not match. I wrote back with more questions, praying that her information does not add mortar to the brick wall.