If William the dancing master, married to Christian OUTERSON, is indeed William son of
James and Margaret (MABON) RICHARDSON, then a direct male line RICHARDSON descendant of William's should show an excellent dna match to RC-3.
Which is looking a good theory to date, even though we aren't comparing apples with apples.
We have an exact match between descendants of the two lines BUT one tested with ancestry, which doesn't test the same markers as those in the Y-DNA37 test of FamilyTree DNA our other participants have used.
So there could be a genetic distance of 0 to 5 between the two.