BMB said:
Saria1, if that is the case, then how could the three older children have their canadian citizenships. None of them were born in Canada, all were born in Mexico and have lived there since they were born. The one child was born in March 2009, and did not receive citizenship until December 2011. She has never lived in Canada, she would have never had a record of landing or confirmation of permanent residence. So how could have this child received their citizenship?
The law changed for kids born after April 2009, if I recall correctly. So the kids born after 2009 are the ones who need citizenship? If yes, then she needs to sponsor them, they are in Canada illegally. First, I'm pretty sure she needs to make sure the kids get legal, I think that can be done by temporary resident visa's, which need renewing every 6 months. Then she can start with this page and read carefully. They need physicals and she needs to fill out the sponsorship paperwork and their PR paperwork. She is better off applying OUTLAND, through Mexico, even though she's in Canada, it's much faster.
http://www.cic.gc.ca/english/immigrate/sponsor/spouse.asp
My best advice is to go into the family sponsorship board and ask in there. So many knowledgeable people who can help them get on the right path, concerning getting the kids legal so she can sponsor them, etc.
http://www.canadavisa.com/canada-immigration-discussion-board/family-class-sponsorship-b5.0/