Hello Bernadine
Geashill is a tricky one, it lies between a few parishes but there is an old graveyard in Geashill village in the Church of Ireland grounds. (This is common enough in Ireland that the graveyard would be beside the Church of Ireland church)
You can check out Offaly.ie and there was a project carred out few years ago surveying all the County graveyards.
https://www.offaly.ie/occ_mini_websites/temp/BurialGrounddatabaseJuly2015.pdf
Burial Ground: Geashill
Denomination: C of I Parish (RC): N/A Diocese (RC): N/A 1838 OSI 6 Inch Map: 1910 OSI 25 Inch Map: 2011 Bing Map: Municipal District: Edenderry Owner: C of I Status: Open Site Description: Old burial ground with adjoining modern lawn cemetery extension, located beside St Mary's C of I church. Boundary: The boundary consists of a high stone wall which is in good condition. Vegetation: The old part of the burial ground has grass with wild flower areas, there are also some conifer trees. New section is a well maintained lawn. Photo 1: Photo 2: Photo 3: Date of Last Visit: 19/06/2014 Location: Located in Geashill village. Access: Via main gate to church and grounds. Parking: Parking located in Geashill village.
In the Griffith Valuations of 1854 there are 3 Sharp families in Geashill area - Benjamine, Robert and Margaret - holding land. (Any of these names sound familiar)
Have you checked out the Irish Census 1821 - there are some Sharp and Sharpe in Offaly but none in Geashill
1901 and 1911 census. Nationalarchives.ie
https://www.killeigh.com/ - Check out this website. Geashill is in the Parish of Killeigh, Co Offaly. You could message them to see if they could be of assistance with burial records and
also you could contact Offalyhistory.com, email - info@offalyhistory.com - there will be a charge for any research they do for you.
Geraldine