I am looking for additional information on the Lewis Allen family and I found your querry,I know this listing is quite old, but here goes.
Robert Allen and Sarah Underwood were the parents of Lewis Allen.Lewis Allen is part of my Row/Rowe family from Lancaster County.The only info I can pass on is that I have them passing between 1850-1860.The census list them as always living in Fawn Twp., York Co., Pa.
Lewis Allen was born in Fawn Twp.The 1850 census lists him living in West Lampeter Twp., Lanc. Co. with his wife's parents, Daniel Row and Elizabeth.She is listed as Sarah Row.I might add that there is a family genealogy listing her as Sarah Parvin. Since my family records list her as Sarah P. Row I hope this is the same lady.I have writen the "owner" of this site, but have yet to head back from him. Louis Allen's wife Sarah was born in Lanc. Co. Pa.I have them buried in Fawn Grove Friends Cemetery, Fawn Grove, York Co., Pa.
I have no idea on the age of this cemetery, but you might call them and see if their records are available to you.Perhaps Lewis's parents are also there.
If you have additional info on Lewis I would apprciate you contacting me through this listing.