Hi,

I am somewhat qualified to answer this I think. I hold both an SA and UK passport and am currently living in Australia. My view is get your/daughters UK passport as quick as you can life is much easier with a UK passport. You can apply for visas on line
Medicare
drivers licence conversion without a test
travelling to anywhere is easier and usually visa free
and generally more acceptable as not being dodgy.

I have three kids in school in Queensland. In primary school and middle school a LOTE is standard but not as strict as they are in SA kids learn the language and progress at there own pace you don’t fail the year if you don’t pass etc. my kids speak English and Afrikaans (my wife is Afrikaans) and enjoyed learning Japanese. When they go on to chooses there own subjects in year 9 they don’t have to choose a second language.

Cheers
Barrow