Thomas Robertson and Mary J Denson

Question

Thomas Robertson (d 1844, Somerset County, MD) and Mary J Denson (b abt 1811, d 1857 in Somerset County, MD) are my gg-grandparents.

Looking for more information on this family.  Parents, siblings, etc.

On My Heritage, a "Carol Robertson" in the UK lists Mary as a gg-grandparent, but I'm not able to contact her.  Anyone able to help put us in contact?

Thanks,

Ralph Willing