Thank you both so much for all this info. You've certainly given me a lot to chew over.
I will have a few goes at linking them to Hugh ... and then Hugh to Julia and Martin.
I found this for Hugh :
16 Dec: Administration (with the Will) of the estate of Hugh O'Dea, late of Cahernaskelleeny Co Galway, RURAL POSTMAN who died 11 Nov 1911 granted at TUAM to Mary CULLINANE, married woman effects £21.8s.0d.
Need a clear head to work out the relationship of Hugh to Mary C, so I'll close for the night.
Thanks again!