When I use a GRO Index or FreeBMD source my citation (Where Within Source) is in the format "Mar qtr 1880 Leeds Reg Dist, 9b 123", so there's nothing in either the source or the citation to indicate whether it comes from the birth, death or marriage index. (Probably a mistake on my part
I've found one possible way to do it, but it's a bit convoluted and I wondered if there was anything better. My way:
1. Use Search and Replace plug-in to change start of citation from "Mar qtr" to "XXMar qtr" - scope of change is sources for Deaths only. Repeat with Jun/Sep/Dec qtrs.
2. Use Replace Selected Source Citations plug-in to convert "GRO Index" source to "GRO Death Index", using Where Within Source contains XX as a criterion. (Or possibly 'contains XXMar', XXJun etc separately)
3. Repeat step 2 to change "Free BMD" to "FreeBMD (Deaths)"
4. Use Search and Replace to change XXMar etc back to Mar (reverse of 1 above).
5. Repeat steps 1-4 with Marriages.
6. This should leave the original GRO Index source referring only to Births, so simply edit its name (and long & short title etc) to "GRO Birth Index", and similarly change "FreeBMD" to "FreeBMD (Births)". (Note: I've left Births till last because the final category doesn't need the same amount of processing and I have more of them.)
Check at each stage with List All Citations for a Source plug-in that nothing untoward has happened. There may also be a few anomalies to sort out manually, such as more recent BMD events that are listed by month rather than quarter. I've already dealt with cases such as where the death index gives an age that can be used as a source for an approximate year of birth.
Finally, it's worth mentioning that I'm finally contemplating upgrading from v.6 to v.7, so if there are any relevant plug-ins etc that work in one but not the other it would be useful to know before I upgrade.
I've done a very limited test of my method on a copy of my project and it seems to work, but can anyone see any flaws in it, or suggest anything better, please?