Here's some pertinent points I've noticed when researching the links;
- The IFHF county sites rarely have records extending into the 20th century.
- IFHF marriage records often only begin in 1845 which is when civil registration commenced for CoI marriages - you may be able to see the basic details of these records (bride-groom-date-place) for free elsewhere. If you want to see if fathers are mentioned, then you will have to buy the IFHF transcript online or purchase a certificate. However, if you chose the former route to enlightenment, here's my cautionary tale ...
- Where the RCB Library catalogues show that baptisms, marriages and burials for a parish all start around the same date, be a bit suspicious - this might be the earliest date of the first entry in the physical register that was used to note all 3 types of events. I've found from experience in looking at some of the original registers that the pages could be filled in out of order with different types of events mixed up too as different clergy chose their own record-keeping style. If the IFHF have got transcripts roughly covering the same periods, check their earliest dates carefully as these might be more reliable.
- Note the variations in spellings of the parish names across different sources - I'm going to write up some more structured tips for dealing with this when searching but in the meantime check carefully. I've made many educated guesses when trying to match up the information across the various sources, so if I've got it wrong, please let me know.
- As you might expect today, the RCB Library has very few original registers for the counties that are now part of Northern Ireland. However, not a great deal has made it online on the corresponding IFHF sites either? I will take a look at the PRONI catalogues for Northern Irish / Ulster CoI parishes and see if I can come up with something that helps show what might be available.