The application for immigration to Canada with my mother was rejected, which affected my child's visa for studying abroad.

If you are over 2 1 year old, you can't apply for Canadian reunion immigration with your mother. As for the children's study visa, if you need to pass the IELTS test at university, you can apply for the university's OFFER. If you are studying in a middle school, you will generally apply through the International Student Enrollment Program of the Canadian Education Bureau, and you will generally be admitted. Pay tuition fees as soon as possible after entering school and provide proof of payment to the Education Bureau. The key is that parents' property certificates should be enough to support the expenses of their children studying abroad. (For example, if you study in 10 grade, it will take you seven years to graduate from 10 grade to university, which is about 1.2 million).