This is a triangulated DNA segment (courtesy of MyHeritage) that I share with a woman from Texas and her two daughters. The red is daughter 1, the yellow is daughter 2, and the orange in the middle is their mom. Interestingly, I share two 6cM DNA segments with daughter 1 that I do not share with the mom. Right now I don't know if those are coincidental or if I'm also related to daughter 1's dad.
After reviewing the mom's family tree, I determined that I am her fourth cousin once removed and a fifth cousin to her two daughters. Our shared ancestors are Joel White (c.1790-) and Rebecca Barnes (c.1795-) of Clay County, Indiana. Her great-great-grandmother was my great-great-great-grandmother's younger sister.
Now that I've figured out how we are related, I can map this portion of Chromosome 2 on my maternal side. I simply download the shared segments from MyHeritage into an Excel spreadsheet...
|Name||Match Name||Chr||Start Location||End Location||Start RSID||End RSID||cMs||SNPs|
...which I then copy and paste into DNA Painter. I did not include the two 6cM DNA segments that I share with daughter 1, partially because they don't meet DNA Painter's default 8cM exclusion and also because I doubt that they're from the same ancestor.
My great-great-great-grandmother was Lydia Celia White (1820-1848), the daughter of Joel White and Rebecca Barnes. At the present time, I cannot tell whether the shared DNA segment came from Joel or Rebecca, so I have assigned it to Lydia (depicted in lemon yellow below). Anyone who shares DNA with me at that location should be related to Joel White and/or Rebecca Barnes.