Why don't you send me a GEDCOM of this family and I can fill you in on the CROMERS and GROSVENORS. The information I had on this family is slightly different from this you stated here.
My wife. Gail Grosvenor CLARKE, is a great-granddaughter of Dr. Alvah W. GROSVENOR -- Elizabeth A. GROSVENOR's older brother. I also have, with a few exceptions, their GROSVENOR lineage back to John GROSVENOR the Immigrant if you want it. I can take the CROMERS back to VA but I do think there was some family connection to CROMERS in SC that I have not, yet, completely figured out.
My email address is firstname.lastname@example.org