I think it would be useful to you to account for daughters of William Brown and Sarah Ann Byron as one or both of them might be cared for in their old age by a daughter. If you can find a burial for daughters, the parent/parents might be buried at the same place.
To that end, who did Charlotte marry, 1908...I cannot see anything in QLD or NSW.
BDM QLD marriage
1908/C2988 KHAN Adalat m. BROWN Jessie
births
1910/C13118 Ethel Martha KHAN Adalat Jessie Brown
1910/C13119 Galarm Gelarlarny KHAN Adalat Jessie Brown
1910/C13119 Golarm Gelarlarny KHAN Adalat Jessie Brown
1910/C13034 Boguin-Noor Madge KHAN Adalat Jessie Brown
deaths
1956/B13630 Boguin-Noor Madge KHAN Adalat Jessie Brown
1917/C3653 Edwin KHAN Adalat Khan Jessie Ann Brown
1940/C1721 Adalat KHAN Buny Moad Berber
1953/B42294 Jessie Ann KHAN William Brown Sarah Byron
Courier Mail 2 Mar 1953
KHAN, Mrs. Jessie Ann. 23 O'Connell Terrace, Bowen Hills. — Relatives and Friends of Mr. and Mrs. R. Austin and Family, Mr. and Mrs. R. Khan. Mr. W. Sounders and Family, Madge, Lorna, and Jack Khan, are respectfully advised that the Funeral of their beloved Mother, Mother-in-law, and Grandmother, Is appointed to leave the Parlour, 400 Wickham Street, Valley, Tomorrow (Tuesday) for Mt. Thompson Crematorium, on conclusion of service commencing at 10.45 a.m.
BDM QLD marriage
1922/C1857 SAUNDERS William m. KHAN Ethel Martha
1934/C365 AUSTIN Robert Sidney m. KHAN Marian Charlotte
BDM NSW marriage
7207/1895 SMITH Robert J F m. BROWN Sarah E LITHGOW
BDM NSW births
13705/1896 SMITH Charles S parents William Sarah LITHGOW
32617/1900 SMITH Ronald E parents William Sarah LITHGOW
31340/1903 SMITH Gladys E parents William Sarah LITHGOW
4702/1906 SMITH Walter B parents William Sarah C LITHGOW
38104/1909 SMITH Laurence R parents William Sarah C LITHGOW