Hello Sandra,
Could I make a plaintive little plea - to everybody. It is always a good idea, when you've made a request on RC and then find out the answer to your question (or find further information) to post again on your query threads so that other RootsChatters don't spend their time and effort searching out information which you already have

Leaving that aside, are you aware of the SeanRuad site where you can search for townlands? It is at:
http://www.thecore.com/seanruad/There is no exact match for Killevey but a search for all townlands in Armagh beginning with 'Kil' might help. Similarly a search for all townlands in Derry beginning with 'Ball' (there are quite a number of these) might give some ideas - especially if the writing on the certificate is hard to decipher (and if the name is just the Registrar's best attempt at rendering a placename told to him in an unfamiliar accent). Perhaps Ballynease-strain might be a possibility?
JAP