Hi Bob. Now that you mention it, yes I have seen Ennis in Catholic records - silly me assuming. Information from Ireland can be very hard to obtain. I did the same (posted letters) but got no reply. But I was given the email address of one family who live in the Duncormick area with the same name - our relationship is not clear as yet, but they have to be related somehow.
Census records for Ireland for 1901 and 1911 should be available on microfilm through Latter Day Saints. BUT, there is a website: www.leitrim-roscommon.com/1901census/
Here you should find some of the families you are after. It says that the information transcribed for Duncormick is complete. I just went down to the SEARCH and put in Co. Wexford, and Civil Parish: Duncormick. Up comes a lot of families - some of which are probably the ones mentioned in your family letters. Hope that site might be of help. I also have a copy of the Griffiths Valuation Index for Duncormick. I can look for people on it for you if you don't already have it.