I came across this potential match (http://www.geni.com/search/matches/6000000015655001071), which led me to this John de Grey as a perhaps key profile in joining these two tree branches -- and perhaps some more MP's in the area would be helpful, too.
Not my expertise ... just a distant ancestor in the region.
@my relation to John De Grey 2nd Baron of Wilton he is my 23 grt grandfather the line is Judy Rice=Arthur Rice my father=Israel Tekarihoken Rice his father=Pierre Atawenrate Rice his father=Ignace Awennaietha Deer Rice his father=Marie Madeleine Kiatawinon Deer Rice his mother=Thomas,aka Atonwa Aronhiowonen her father=Silas Rice his father=Edmund Rice his father=Samuel Rice his father=Thomasine Frost his mother=Thomasine Frost (Belgrave)her mother=John Belgrave 111 Her Father=Richard Belgrave his father=John Belgrave his father=richard Belgrave his father=John Belgrave his father this is my linage Judy Rice