Many thanks for your perseverance. I guess I don't want to accept that Donald was illegitimate ! Apparently from those who remembered her she was a 'lady'. However - it happens!
About Chapel Street - William could have moved between John putting him down as next of kin in 1890, and the 1891 census. I did find a William on Chapel St. in 1901 married to Ada with 3 children.... and I found them in Durham in 1891 and he came from Birmingham. If it is his brother he is 9 years older.
This John Davies, 'husband' of Margaret , has a middle name of Eric at least on his death deeds and in the electoral roll for 1912. However I have searched several times and cannot find such a name nor even John E who would fit any of the criteria. This is why I didn't give you this information before. So you can discount any John's with any other initial.
I'm going to the library tomorrow to find Margaret Davies, born Bolton, on the census of 1891 to see who the possible parents are.
I quite understand if you want to draw a line under this. It is quite complicated and frustrating.