Thank you so much for the wealth of sources and incredibly helpful further research pointers.
I will follow these up over the next couple of weeks. There is a family rumor that the name 'Demel' or 'Dehmel' came from Frieda Ottman's mother's (Iden)family place of origin (near Hamburg) in Germany; or possibly that Frieda choose the name after the German poet Richard Dehmel
I should have also emphasized that my (probable) g grandmother was from a wealthy family and married to a very wealthy man. She would have been able to afford to employ private nurses to help her give birth. She was also not a Roman Catholic (Presbetarian) but the baby Joyce Frieda Gunn was later described as Roman Catholic.
Thank you again for all your help