I received the following question, which I think is excellent.
Is there any software for plotting possible/probable relationships to MRCA [most recent common ancestor] for groups of 10-1,000 cousin matches suggested by various services, e.g. 23andMe, GEDmatch, FTDNA?
It seems to me that standard genealogical services are too rigid. Once you lay down a line of possible 3rd cousins and another for 4th cousins etc, linking them to various MRCAs who are perhaps 5 or 6 away becomes a bit of a nightmare.
The cousin matches referred to are typically based on shared segments longer than some threshold (typically 5 cM.) that appear to be identical by descent (IBD). In my case, 23andMe identifies 835 relatives but I know how I am related to only two (my mother and my sister).
I will contact scientists I know who work in this field to see if there is any software that is available to, and usable by, the general (informed, curious and sophisticated) public.
If you know of software that might be useful and want to see some of this data, I can send examples from 23andMe. It lists all IBD regions longer than the threshold that are shared with the user. Someone using this tool for genealogy will typically have such data for a small number of family members, and the information about most "cousins" is typically minimal. The person who posed this question can probably files to anyone who wants to see what they look like.