Where can I locate records mid to late 1700's for Down County, Ireland. (family may be in Blaris.
Blaris is in the Diocese of Down and Connor which crosses the Antrim/Down line.
Any records that early would be church records, and the NLI shows no RC registers available. https://registers.nli.ie/parishes/0451
You may also want to join the Ireland Research group https://community.familysearch.org/en/group/104-ireland-research. There are some amazing resources listed at the top of the group page.