✔ 最佳答案
I'm currently studying in Canada.
I was born in Canada, but I've lived in HK for 14 years, and I used to study in Australia too. So, I hope I can help u and your relatives by answering your question.
First of all, the one who is 10 year-old will be in grade 4, and the one who is 15 year-old will be in grade 9. They don't have to retake primary school in Canada, WASTE OF TIME. If they really have difficulties in English, ESL(English as Second Language) is provided in schools other than regular English courses. They will have to pass ESL courses first in order to take regular English courses. ESL is divded into 5 levels (A-E).
No matter which school you wanna get into (private/public), there's only 1 price for new international students when they first come to Canada - $13000 Canadian dollars.