Dear all
Just to report back, I did get a DNA sample tested and now have the results back. Very interesting reading but I need to study further to really understand what they mean. Two things stand out immediately;
(a) Another Milliken researcher and I had extended our family trees using informed guesswork and circumstantial evidence (as you do) and came to the conclusion that we had a common ancestor in mid 1700's. Then two brothers in the Belfast area about 1800 prior to the divergence. These parts of our research are not verified by paper evidence thus we realise they can not be relied on

When my results were added to the Milliken surname project I found that I had a very close genetic match with this researcher to the extent that we would be considered close DNA cousins!! (One mutation in 43 markers). Unfortunately it is not possible to accurately date when that mutation occured

(b) Another Milliken researcher I have corresponded with for several years was researching a related cousin family but we assumed there was no direct link. The origins were a group of brothers that crossed from Scotland in the religeous wars of the 17th Century.
Lo and behold we had an exact match on the DNA so here is another DNA cousin sometime within the last couple of hundred years, perhaps much more recent divergence than the 17th Century. I need to learn more.
So no absolute answers from the test but it gives me a reason to focus on researching into these two families to find the common links

Gary