Those tricky DNA circles

I have began working thru the probate records of my Paternal Grandfather's Ogilvie and Harris lines which come together at my 5th Great Grandparents. My tree is at Ancestry where I have tested along with my sister and my Mom.  All of our DNA results are at GEDmatch as well.  As I work and look thru hints I like to check the profiles of others who have linked to or uploaded information.  When I visit their profile it also lets me check to see if there is a DNA match between me and that person.   I can also select other tests I admin to see if any of them match.  One of the good things about this is that if that person manages any other test and they match the test you have selected they will also appear beneath that profile, even if you don't match the profile but do have a match with one or more test which they admin.

Clicking on the word "your" lets you select other tests you admin to check against their profile

It's unclear to me when you don't find a match if it means they don't match you or if perhaps they haven't tested.  At this point I only give weight to the matches...and not any additional when they don't because I don't know if they have tested.

In this particular case my sister has the larger matches(17-20 cM segment) with both of these persons who tested and my Moderate match with the D.E. kit is only 6.6 cMs.  Ancestry has put us all in the Ann Knox circle together.  At this point there is not a Ogilvie or Harris Circle even though I do see descendants from at least 4 lines that descend from them working on trees.  Likely not enough of them have tested or the ones that have tested do not have DNA in common.  I contacted the main profile person and heard back from them within an hour(almost a record).  Now here is where it gets tricky.  The researcher has several tests at Ancestry(self, parent, sibling and maternal uncle) Along with the being included in the Ann Knox Circle for the testers profile, Shared Ancestor Hints for  Jacob Sutton and wife Ann Knox are shown as well as William Ogilvie and Mary Harris.   Since the Sutton/Knox and Ogilvie/Harris are on different sides of the main testers family we were able to determine that the match my sister has with  her is likely Ogilvie/Harris.  Looking at others who match at smaller amounts along the same segment and knowing the likely line, I have been able to find several others who appear to all have lineage back to this Ogilvie/Harris couple though I am still working on it.  To add too this.  The particular segment along which my sister(we are full siblings) matches is one which I and my sister do not have in common.  For that segment I have matches which come from our Paternal Grandmother's side of the family  This helps to know because it tells me if I match my PGM and my sister doesn't match me along that segment, that she got the only other segment that Dad could have given her....the one he got from his Dad, our PGF.

This is why it is important to look at the matching segments rather than rely on the DNA circles.  I cannot stress that enough.  I feel like the best approach to the DNA circles is to work them looking over the matches and trying to get as many as possible that match you at large amounts to GEDmatch where you can examine them more closely and prove or disprove each of the matches for that circle.