It is not uncommon for immigrants to bring over their parents into Canada after say age 55, obtain PR status and then after the 10 years to qualify for OAS, they start obtaining OAS or GIS - this is WRONG and should not be allowed to occur.
For both OAS and GIS there needs to be a means test that if the individual comes to Canada after the age of 45 under some parent/grandparent reunification plan and that individual does not work 10 of years in Canada, (the time period from 45-55yrs old), that they do no qualify for OAS or GIS - full stop when they turn 65 or any other year unless than have worked for 10yrs, equal to the 10yrs of residency required to obtain OAS and GIS.