The names Robert and Malinda do not typically run in our family line since coming to America, in fact in older generations I know of none and I know the braches of our line fairly well although not in total.
There are no branches in our first generation US that went to VA. However when you get this far back it is VERY importent you learn the history of the regions also. I am finding this puts huge kinks in things. For instance in the Mid 1700 a substacial ammount of what is present day VA Maryland and WVa was part of the Coloney of PA; if you look of maps of the day the PA boarder was 50-100 miles south of the present boarder. Also remember there was no WVA it was VA: and when they were plotting SW PA in 1781 it was wilderness and there was a land dispute between VA and PA over present day SW PA clear up to Pittsburgh. The area was know as Ohio County, Westmoreland County VA, and others before becoming Washington County PA in '81. Then that Washington County has split off Green County.
OK, it is pretty obvious that Robert Carson XXX, mother was a Carson and her father was probably Robert. Which most likely makes him the second son. There was a practice at that time to name the first son for the paternal Grandfather, 2nd for the material Grandfather, 3ed for either the Father or the Paternial Great Grandfather and the 4th for the other of the two, the 5th for the Maternal GGrandfather. Daughters were opposite but the same pattern; first for the material grandmother and so on. This was a practice out of both Scotish/Irish and German families, although not a rule.
Back to your situation. There are Robert Carson's and other Thomas's out of Lanchaster PA, a large group. I have a very distant cousin in the Carolina's related to this branch but we cannot make the paper connection between our families. DNA indicates we have a common male relation between 8-12 generations back at 90% probability and 99% at 13-16 generations. We know our lines do not link for the last 8 generations since coming to America and as you may know Records in Ireland were lost in a fire around 1900.
So you might check with him. I will forward your email to him to contact you. I don't give out emails of others without their approval.
Somewhere way back I am sure there is a family tie, although there are two Carson DNA lines that don't link together for 30.000 years. One is Scotch/Celtic (R Halogroup) , the other is Scotch/Nordic (I Halogroup), which is mine.
Oh typing that there is another thought. There is another Thomas Carson in Western Washington Co., PA; I had heard this in the past but did find him also listed with the DAR. This Thomas and Mine were both born in Ireland within 5 years of each other, came to America nearly the same time, Died within two years of each other. I've not looked much into this other but they have completely different wives, childrens name's between the families and I believe he is on the DNA project as an R type which means no relationship to speak of at all.