I'm filling in my Chromosome chart little by little. Thankfully I'm now seeing some 2nd cousin matching segments. Not at GEDmatch or Familytree DNA, but instead at 23andMe and MyHeritage.
Since my mother tested I am able to separate my matches according to which parent I may have received a segment, or segments, from.
When I have segment data for matches I at least try to mark them according to which Grandparent they likely came from.That is easy when it comes to separating my Maternal line. Nicaraguan segments from my Grandmother Del Castillo are easy to separate from my Grandfather Forgey's Northern European segments. A high percentage of Native American and some African admixture signals a Nicaraguan match.
Separating my father's parents lines is more difficult since they both have European heritage. My Grandfather Kapple's family was from Burgenland, Austria. If someone has a tree with Burgenland ancestors I mark these segments as Kapple/Kurta, or more specifically if they have the same ancestors listed. My Mason grandmother had Irish, French Canadian, and some Early American Heritage. If I can find specific names associated with her family I mark her matches, or specific places like Pollaturick, Ireland.
This week I was able to see some 2nd cousin matches segments for the first time. One of these matches is a Kapple 2nd cousin. I'm certain these large segments are identical my descent. I know they come from ancestors in Burgenland, Austria. I also have a Mason 2nd cousin match. I'm not sure where geographically these segments trace too? They are helpful though in narrowing down which great-grandparents these segments may have came from
My expanding segment map helps me sort matches. If someone matches on my maternal or paternal side and matches in the same place I can infer they must descend from the ancestors that passed the segment down to me. Having 2nd cousin segments increases my confidence in my mapped regions. I'm hoping to fill in this map even more now that MyHeritage is offering segment data.