hi anonymous, I'm confident that Christine has identified the family in the census and the children's births (below are the record transcriptions from findmypast.co.uk for comparison). Spelling variations can catch you out and I nearly missed the marriage for your greatgrandparents but here are the details...
Groom: MARTINSON, Morris
Bride: PURCHELL, Amelia
Registration district: Mile End Old Town
County: London
Year of registration: 1906
Quarter of registration: Oct-Nov-Dec
Volume no: 1C
Page no: 731
Children's birth records as follows (Fanny = Amy Frances, & Mary = Miriam) with Rosa born after the census...
Name: MARTINSON, Annie
Registration district: Mile End Old Town
County: London
Year of registration: 1907
Quarter of registration: Apr-May-Jun
Mother's maiden name: Not available before 1911 Q3
Volume no: 1C
Page no: 433
Name: MARTINSON, Amy Frances
Registration district: Mile End Old Town
County: London
Year of registration: 1909
Quarter of registration: Jan-Feb-Mar
Mother's maiden name: Not available before 1911 Q3
Volume no: 1C
Page no: 363
Name: MARTINSON, Miriam
Registration district: St. George in the East
County: London
Year of registration: 1911
Quarter of registration: Oct-Nov-Dec
Mother's maiden name: Purcell
Volume no: 1C
Page no: 521
Name: MARTINSON, Rosa
Registration district: Mile End Old Town
County: London
Year of registration: 1913
Quarter of registration: Jan-Feb-Mar
Mother's maiden name: Purcell
Volume no: 1C
Page no: 750
There is no sign of Morris in the 1901 census so he may have entered the country 1901-1906 but Amelia appears in the 1901 census at home with parents and numerous siblings...
PURCELL, John Head Married M 45 1856 Road Labourer Yorkshire
PURCELL, Mary Wife Married F 37 1864 Shadwell, London
PURCELL, Rose Daughter Single F 17 1884 Rope Worker Shadwell, London
PURCELL, Alice Daughter Single F 15 1886 Rope Worker Shadwell, London
PURCELL, Walter Son Single M 13 1888 Shadwell, London
PURCELL, Amelia Daughter Single F 11 1890 Shadwell, London
PURCELL, George Son Single M 9 1892 Shadwell, London
PURCELL, Fanny Daughter Single F 7 1894 Shadwell, London
PURCELL, Emma Daughter Single F 5 1896 Shadwell, London
PURCELL, Hannah Daughter Single F 3 1898 Shadwell, London
Piece: 349 Folio: 51 Page: 33 Registration District: Poplar Civil Parish: Bromley
Address: 23, Eastward Street, Bromley, London County: London