Anyone can apply for anything. The issue is whether or not the applications will be approved. They are not eligible for study permits so their study permit applications should be refused. Is it possible they could be granted them due to a mistake? Sure, I guess so.
Given how long your family has not been in Canada, PRTDs are not good options. (If they apply for PRTDs and the government figures out how long they've been outside of Canada, their statuses will be revoked and you will have to sponsor them. Assuming your PR Card is still valid.)
The only viable option, under normal circumstances, would be to come to the US and attempt to enter Canada by private vehicle (i.e. car). The border is closed until June 21, though it is open to PRs. (Of course, if the only proof you have is your Records of Landing/COPRs from 2012, that could be an issue.) It may open then or it may be delayed. Canada is vaccinating like crazy right now so it's possible that the border will open then. There is still risk with this option as it is possible that their statuses could be revoked while attempting to enter.