Martha:
I checked the 1863 Griffiths Valuation head of household listing for Kilkeel parish and there were no Dorris or Doris entries.
What time period did the Dorris family members leave Ireland?
I did look at www.familysearch.org entered Dorris and Irish births and there were a good number in Belfast and Co. Monaghan 1880s and later. You may want to check out the site.
Roger McDonnell