Adoption research

I've gone off the deep end on a side project. My eldest daughter, Carmen, has a close work friend who was adopted during infancy. Work friend, let's call her "L", recently took an Ancestry DNA test and asked for my assistance to see if I could help her find her birth sister. I said "I'll give it a try" and have now built her a family tree of 1,897 persons, biologically connected to her, but none can be confirmed as her birth parents or birth sibling. Yikes!

It's been quite an adventure and stalled all my work, research and scanning related to my own family tree lines. First, she has no close DNA matches. Her closest match is listed as "LastName" and has no tree, no information, and no other close matches.

One of her parent's appears to have come from a family of 9 siblings, none who have DNA tested and all who have been pretty good at locking down their data. I've loaded L's DNA to other genealogy sites (with her permission, of course) and found nothing more helpful.

Her other parent's line is an endogamy nightmare. I thought my family line who all lived in Luverne, Minnesota, had some endogamy challenges, but nothing like this line. They descend from both Mennonites and original polygamous Mormons, including an ancestor who is included in Joseph Smith's History of the Church of Latter Day Saints. One of L's Shared Matches has 6 known sets of common ancestral lines; normally, people share 1 set of common ancestors.

On top of some health challenges which impair my analytical skills and comprehension, I constantly debate giving up versus trudging forward. In my mental prime, maybe there was a chance, but now, I mess up simple things often; good thing a tree like this is easily forgiving, as long as I don't lead her on to the wrong final result. I used to be very passionate about genetics and even wrote a 20+ research paper on genetic engineering; now I try to watch a video about DNA tricks for genealogy and my head is splitting 60 seconds in. 

If you read this far in to this post, send me a note and let me know your thoughts. Trudge forward or call it quits?