If they even know one another, it’s not going to be through that family tree. It’s going to be through their power positions.
People lose track of their families somewhere in the great grandparents period. Parents tell children their stories. Grandparents tell of their parents. And some of that is remembered. But there is no one to tell the stories of the great grandparents, and so the relationships are lost.
Unless you are in a secluded area or live in a ten x ten mile section of our county where the relatives of ten families came over from Germany in about 1840. When I arrived in 1970 they were still speaking German and teaching their children in one room classrooms They have intermarried so much they MUST keep the trees branches straight. Sisters married brothers repeatedly. Cousins married cousins (I know ). ITs kind of like the Amish. No one moved out of the area and few outsiders were accepted past the porch