When Margaret married David Price her surname was Alexander. See index of marriage registration below.
Digger - Pioneer Index. Victoria 1836-1888
Surname: PRICE
Given Names: David
Event: M
Spouse Surname/Father: ALEXANDER
Spouse Gvn Names/Mother: Margaret
Year: 1859
Reg Number: 2203
Margaret used the surname Alexander at all births & deaths of her children except one, where she used Darling. See below:
Digger - Pioneer Index. Victoria 1836-1888
Surname: PRICE
Given Names: Frances Darling
Event: B
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret ALLEXANDER
Birth Place: YANDOIT
Year: 1860
Reg Number: 21459
Surname: PRICE
Given Names: Jessie
Event: B
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret ALEXANDER
Birth Place: FRAN
Year: 1862
Reg Number: 24385
Surname: PRICE
Given Names: Elizabeth
Event: B
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret DARLING
Birth Place: EMER
Year: 1864
Reg Number: 14996
Surname: PRICE
Given Names: William
Event: B
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret ALEXANDER
Birth Place: EMLD HILL
Year: 1866
Reg Number: 14541
Surname: PRICE
Given Names: David
Event: B
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret ALEXANDER
Birth Place: EMERALD HL
Year: 1869
Reg Number: 2289
Surname: PRICE
Given Names: David
Event: D
Spouse Surname/Father: David
Spouse Gvn Names/Mother: Margaret ALEXANDER
Age: 2
Birth Place: EMERALD HILL [now South Melbourne]
Year: 1871
Reg Number: 8338