At least a couple of descendants of this family have posts on this McKee Forum.Run a search using Stewart as your search word on this forum list of messages.
One message at 4868 and another at 4871 will give you the descendants' previous posts and posts on this McKee Forum also.
James Stewart may still be monitoring new messages here and also Richard Brown.Also, other descendants of the large group that Stewart researches with may see your post and help you out.
Stewart has documented this line better than anyone I have emailed with but that does mean I've heard from all who have also worked on this line.I waited a couple days following your post to see if you would receive other posts to your query as it has been several years and a couple of dead computers ago that I also worked on this lineage.
I believe this McKie / McKee line is allied with my McKee ancestors by yDNA if we ever find a known male McKie-McKee to test for this "Robert McKie / McKee the Elder" family.
My husband is at kit 127187 on the Family Tree DNA McKee Group and the majority of McKee having tested thus far alsobelong to this R1b M222+ Haplogroup.That does not mean this will be the ultimate haplogroup for McKee but it is all we have to go on at the present time.So, it appears to be dominant and increases the odds of new males with the McKee surname being M222+ somewhat.We also have other haplogroups represented and it is always exciting to find members of the other haplogroups.
If you are not successful with contact attempts to Stewart or Brown let me know and I will see if I can help you further.