That is neat that you have a male MILLS available who might be available to do DNA testing.
I know what you are saying, sort of how my cousins and I also felt about our lines of MILLS. We found no link to any one else, back then either (late 2004).
My file on www.rootsweb.ancestry.com
is called chekwriter
it is called MILLS family or FISCHER family.
My grand father is George Washington MILLS B: 1857 Montgomery Co OH, and my grand mother was Grace E GREEN B: 1884 Beebe, AR.
You can check out my files, I have attached the DNA results to them as well.
Both for MILLS and FISCHER.
I think it would be better for you to ask your siblings and or other relatives about the DNA thing, than for me, out of the cold asking. They would think it was a scam or other.
Can chek out that DNA website right now, they are offering a special prices for testing.