Hi!
Checking back to see how your search is coming. I tried the library closest to Brandywine, MD (which is now in Prince George's County). They do not have a vertical file on the family. The library in Charles County, MD has very little except to refer me to Heritage Quest. However, I remembered that the College of Southern Maryland, which is in Charles County, MD has a Southern Maryland Studies Center (SMSC) at the LaPlata, MD campus. 301-934-7606. The reference librarian may be of help in your Proctor search.