By far the best website for information on these lines is https://mccutcheonsfromdonaghadee.wordpress.com/. It is this website that provides the linguist argument for these McCutcheon-Campbells possibly being originally MacEacherns, a family that Campbell legend has a story about involving the Campbells of Craignish. The page on that website that makes the case is titled “Chapter 2: The Name McCutcheon: A Study: the Evolution of a name spanning 255 years“. What is interesting is that while laying out the various spellings of the name, she mentions the Y-DNA results in the Project (Although a bit dated now).
She gives these names as all being from one family: McHutcheon; McCutcheon; McQuisten; McQueston; McEachern, McEachan. Traditional;ly such claims have not worked out well (See PC Campbell and his claims about McIver). However in this case I saw at least one instance where the same man was referred to both ways on the same day! So while not every example may be correct, we only need one to make the link between McCutcheon and McEachern.
McEachern in and of itself is likely problematic because as far as i know that name has always been associated with Clan Donald if I recall correctly. However, there is the story I mentioned involving the Campbells of Craignish, who were also thought not to be related to the Campbells of Lochow up until October 2023, when the BigY test results showed otherwise! I will try to relocate the story, and if I recall, there was one person that wrote about that MacEachern being already related to the Campells of Craignish and the account of the marriage was simply one of keeping the lands in the family. It may be the wrong family unless by females lines? That is what I hope we can determine with this group’s focus.