1881 census

1891 census

1901 census

Possibly worked together, as both are Iron Moulders in 1901.
This could be how Richard (Dick) met and later married Lily, John's eldest daughter.

Cheshire Birth indexes for the years: 1874
MERCER    Herbert Dutton     Birkenhead, Wirral    BIR/99/84

In Lil Mercers notes, she is recorded as eldest daighter of John Mercer

Aged 24 in 1901
DOB Confirmed by 1939 Register

Cheshire Birth indexes for the years: 1876
MERCER    Lily     Birkenhead, Wirral    BIR/107/89

Name:    Lily Mercer
Gender:    Female
Baptism Date:    4 Mar 1877
Baptism Place:    Birkenhead, Cheshire, England
Father:    John Robert Mercer
Mother:    Emily Ann Mercer
FHL Film Number:    2104340

Sadly nobody wrote the date of the obituary, namely Alice in Newspaper clipping of Bolton reads:
Lilly Mercer & Richard Mather married May 23rd, 1904 at Cathcart Street Baptist Church, Richard youngest son of Joseph Mather to Lily Mercer eldest daughter of John Mercer both of this Town.

Sue believes all her grandparents except Lily Doxey died around 1956/7.  There are several matching death in the index from 1954 to 1960, but none matches perfecty :-

Oct-Dec 1954 Lily MATHER, 62, Barton, 10b 266
Apr-Jun 1955  Lily MATHER, 61, Middleton, 10e 489
Jan-Mar 1958  Lily MATHER, 74, Farnworth, 10c 227
Jul-Sep  1958  Lillie MATHER, 73, Bolton, 10b 524
Apr-Jun 1960  Lily MATHER, 63, Salford, 10f 471
Jul-Sep  1960  Lily MATHER, 83, Manchester, 10e 188  (BEST)

All except the last record appear to have died too young if Lily Mather (nee Mercer) was born in Dec-1876.  Probably the Last record is correct and Lily died (actually death recorded) in Manchester, but the obituary was in Bolton as that is where she once lived.  Sue would have only been 7, so still a young child and not remember Lil much!

MATHER Lilly of 34 Hemmons Road, Longsight, Manchester 12 widow died 23 September 1960. Probate Manchester 31 October to Kenneth James Turner Schoolteacher. Effects £1,155 1s. 10d.

Aged 22 in 1901

Cheshire Birth indexes for the years: 1879
MERCER    Douglas         Birkenhead, Wirral    BIR/116/42

Aged 19 in 1901

Cheshire Birth indexes for the years: 1882
MERCER    Sidney         Birkenhead, Wirral    BIR/127/60

Born 1685 (1891 census)
Born 1687 (1901 census)

Lancashire Birth indexes for the years: 1885
MERCER    Florence         Prescot    PRE/49/90

Born about 1889 according to 1901 ensus.

Several Edith Mercer births in Lancashire around this time, but the first one seems a likely march:

Lancashire Birth indexes for the years: 1888
MERCER    Edith         Prescot    PRE/53/4
(Florence was also registeded at Prescot in 1885 and Ernest in 1891)

Births Sep 1888   (>99%)
MERCER  Edith     Prescot  8b 656

Births Jun 1889   (>99%)
Mercer  Edith Maud     W. Derby  8b 271

Aged 7months in 1891

Lancashire Birth indexes for the years: 1891
MERCER    Ernest         Prescot    PRE/56/54

Florence, Edith and Ernest births were all registered at Prescot, so it is likely William was too:

Lancashire Birth indexes for the years: 1893
MERCER    William W         Prescot    PRE/59/97
or
Lancashire Birth indexes for the years: 1894
MERCER    William A         Prescot    PRE/61/41