My mom got multiple entry visa and she will come to Canada to stay with my
family for most of the time. I will sponsor her under family sponsorship
as soon as they open the program again.

I am wondering after I receive the approval in principle and the file is
opened at the Canadian visa office, does my mom have to go back to home
country to mail forms and documents, undergo medical exams and attend the
interview?

Will she be able to do it in Canada if her visa is still valid?

I would appreciate it if anyone can help me.

Thank you!

Hi,

your mom can stay in Canada as a temporary resident for as long as CBSA officer approved it at the time of entry into Canada (usually 6 months at a time, after that it can be extended). After Case Processing Centre in Mississauga sends you a letter informing you that you can sponsor your mom all the documents will have to be sent to the visa office in the country where your mother normally resides. She may be asked to attend the interview there however she can complete medical exam in Canada, she can find a CIC approved doctor here: http://www.cic.gc.ca/dmp-md/medical.aspx

If interview is not required she may be able to stay in Canada while your/her application is being processed. She can even get PR status (land) at CIC office in Canada.

Instruction for the sponsor (you): http://www.cic.gc.ca/english/informatio ... family.asp
Instructions and forms for your mom: http://www.cic.gc.ca/english/informatio ... famcls.asp
Your mom should also read instructions specific for the visa office in her country of residence.

hope this helps.

Milorad