Hi Jess

Welcome to rootschat.
I will detail Bruno's birth so others searching will have his parents' names. May help identify him in the death indexes.
HINZE Bruno Alfred August
23 Aug 1870
Father Henry HINZE Mother Maria Elisabeth SEIBOTH
At Lyndoch Bar 86/519
and marriage
DOLLMAN Lillian Blanche Elizabeth b. Birmingham
BENTLEY Wilfred b. Adelaide
1897 Reg#5309
It would appear by the birth names of Alice in 1892 they had a relationship prior to the marriage.
Births I can find
DOLLMAAN Alice Bentley
Father Unknown Mother Lillian Blanche DOLLMAAN
At Scoresby 1892 Reg#36325
DOLLMAAN Florence Ethel
Father Unknown Mother Liln Blanche DOLLMAAN
At Scoresby 1894 Reg#6837
DOLLMAAN Alma Gladys
Father Unknown Mother Lillian Blanche DOLLMAAN
At Scoresby 1895 Reg#15796
DOLLMAN Vera Kathleen
Father Unknown Mother Lillian Blanche DOLLMAN
At Box Hill 1897 Reg#16898
BENTLEY Errol Lionel
4 Dec 1902
Father Wilfrid BENTLEY Mother Lillian DOLLMAN
At Gawler South PtG 705/125
I notice this death as HINTZ
HINTZ Alice Emily
26 Dec 1910 19 years Status Not known
Relative Bruno HINTZ [Father]Residence Williamstown Death Place Adelaide Ade H 354/137
I notice that Bruno's parents both died at Williamstown.
As you have Lilian's date of death you could ring the Adelaide Cemeteries Authority that manages West Terrace and other cemeteries. It may help them locate her burial in their register. Perhaps you could ask them to check the other cemeteries they manage as well.
http://aca.sa.gov.au/west-terrace-cemetery/index.phpContact details on website.
I note that Lilian died in hospital...do you have her death cert? - Unfortunately in 1904 place of burial was not included on death certificates.
BENTLEY Lilian
23 Jul 1904 34 years Status Married Relative Wilfred BENTLEY [Husband]
Residence Parkside Death Place Adelaide Ade Symbol H 303/366
Hope the ACE can help you.
Cheers
Cando