If the following locally born children are ALL theirs, it looks like Alice's maiden name was DUNMORE. There is certainly no repetition of first names, increasing the possibility that these were all children from the same family.
Births Jun 1900 Hebditch Dorothy Hilda Steyning 2b 292 + 1911 census
Called Daisy, born Brighton on 1901 census
Births Mar 1902 Hebditch Frederick George Steyning 2b 264 + 1911 census
Births Sep 1905 Hebditch William Sidney Steyning 2b 270
Died Brighton 1907
Births Sep 1908 Hebditch William Charles Steyning 2b 251 + 1911 census
Births Mar 1911 Hebditch Thomas G Steyning 2b 232 + 1911 census
died steyning 1911
Births Sep 1912 Hebditch Lily M Dunmore Steyning 2b 470
died Brighton 1914
Births Dec 1913 Hebditch Walter R H Dunmore Steyning 2b 430
Births Mar 1915 Hebditch George A Dunmore Steyning 2b 435
Births Mar 1917 Hebditch Margaret H Dunmore Steyning 2b 375
died Steyning 1920
Births Sep 1919 Hebditch Laurence P Dunmore Steyning 2b 370
died Steyning 1920
Births Sep 1921 Hebditch Irene Dunmore Steyning 2b 468
Births Jun 1924 Hebditch James Dunmore Steyning 2b 384
If Alice was born 1871, can't positively identify Alice or Frederick's birth on FreeBMD or their marriage, although there was a marriage of an Alice Dunmore to a Frederick RAMSEY in 1900
I seriously doubt whether Alice was born c 1871 as stated on the 1901 census index.
My reasoning is that if all the above children were theirs and Alice was born c 1871, she would have been pushing it a bit to have her last child when she was 53. The 1911 census however gives Alice Hebditch of Hove a birth year of c1881 and that is supported by two Alice Dumores born around that time. Either could fit the bill so you still need to find the m cert to establish who her father was.
Suggestion
Not all the Steyning entries are on FreeBMD, so check for a Hebditch-Dunmore marriage on the main GRO indexes.
Roy G
