My Search for Great Granny Dickens form. Walker nee Billings

I am looking for my Great Grand Mother in the UK 1881 Census.

She is Phoebe Billings b. 9 Mar 1842.

She married Robert Walker b. 20 Feb 1839 on 17 Nov 1861 at St Martin's in Birmingham.

The 1881 Census should show the family as follows, with or without Robert as he may have died by the time the census was taken:

Phoebe Walker or Dickens (39) in Smethwick,Staffs, warks or Worcs.
She should have with her Children:
Louisa (19),
Elizabeth (18),
Ada (17),
Albert (8),
Robert (6) {Robert is my Grandfather}
Edwin (3)!

Of course the older girls may have been working elsewhere, but none of them married until 1883 and after, but I beleve the 3 boys at least should be with Phoebe.

We know that Phoebe was married to Robert Walker in 1861 we have the certificate. However, when Phoebe's son Robert, my Grandfather Robert was born in 1875, his birth certificate shows the father as Robert DICKENS, as does the birth certificate for his brother Edwin in 1878.

We have been unable to locate a death reference for Robert Walker, but we have the marriage certificate for Phoebe marrying Thomas DICKENS in 1883. Thomas was a widower, previously married to ELiza Pearsall.

On the 1891 census Thomas, Phoebe, Robert and Edwin are there as DICKENS. They had another son Levi in 1885 but he died in 1886.

When Robert married my Grand Mother Emily Thompson, he gives his name as Robert Victor Walker, Victor being an assumed middle name, and from then Robert remains a Walker.

I have searched the 1881 census for Phoebe, Billins, Billing, Billings, Walker, Dickens, Dicken and Dirkin as it appears on the 1911 census. I have searchd for Robert and Edwin in the same way.
Thanks

Caroline