I'm now completely sure that this is the correct family. The address on the registration on Hannah Kenny's death and Daniel's death is the same as the address on my great-grandmother & great-grandfather marriage certificate.
It must have been that Lilian is the same person as Elizabeth Ellen. My mum was saying that a member of family on her side had no idea that she was 3 years older then she thought she was, so it's obviously not completely unheard of to not know your actual birth date in this time period. Hannah Kenny couldn't read or write so perhaps she didn't really know the exact dates of her children's births.
I must say a big thank you to you both Sinann and Dathai! You got me so much further in my research in one day than I could ever have done by myself!