I can't find a connection; however, I'm compelled to wonder if they are connected to some lost lines.
I show the earliest Sites (to actually use that spelling) was Jeremiah Sites believed to have been born in Germany in March 1817.He had 3 sons.
One of this sons was John C who was the victim of census takers misspelling of his name.I've seen it spelled Sietes.I am 99% sure he is a son because he John lived next door to George "Sietes" according to the census, and the information on this George "Sietes" (his family, etc.) is the same as my George Sites from whom I descend.
I show that John (born about 1841) married a Mary Agnes and had at least one daughter, Louisa.
Now, John and George had another brother named Andrew (born about 1838).Andrew would have been about 26 when the Civil War hit the Gettsyburg area.I know that both their father Jeremiah and George joined the Union (largely just to help get the Confederates off their property!).
So it would be likely that Andrew also joined, but I have absolutely no information on Andrew.He just vanishes.
So, you might want to see if you can make any connections to Andrew or John Sites.Incidentally, their brother George had 18 kids, so I can see something like that running in the family!