I am confused and hardly know where to start with the questions.

I know they boarded up Pigott's scrape with the broken glass, but now where is the cubby you all refer to? Is it suitable for nesting? And has Beauty been copulating with both Dot.ca and the newly arrived unbanded tiercel? And did she not also copulate with the UT who was around before DC came back from migration? If Beauty lays eggs, how will anyone know who the male parent is? Maybe this is one way of broadening the gene pool for peregrines but it might make a real mess of the family tree.

Dot in PA
Pigott's cubby-I don't know the actual layout, but I recall it being described as a sheltered nook. Sounded like a reasonable scrape site, but no one has seen the actual spot.
[edit-hope this doesn't break the rules-please fee free to edit if I said too much]-It appears this UT is the same UT Beauty was with in the week before Dot returned from migration. Have they copulated? One instance that MAK saw today is all we know for sure.
-Doesn't really matter who the Daddy is in the end. As long as one or both support Beauty.
I took Cornell's Courtship & Rivalry in Birds course this winter. A young male sneaking into an established pair and adding himself into the gene pool is quite common in smaller birds. Before so many pefas were banded, who knows how often this might have happened.