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if ur usband has the permanent card and has already mentioned his kids in the application forms he did when u applied for him , the answer then is yes he can sponsor them
 
He's right, if your children are included on your husband's application before and met the requirements, then it should be fine. Check this link http://www.cic.gc.ca/english/immigrate/sponsor/spouse-apply-who.asp

You may also want to take note of this, it's from the said website:
"Dependent children
A son or daughter is dependent when the child:
is under the age of 22 and does not have a spouse or common-law partner
is a full-time student and is substantially dependent on a parent for financial support since before the age of 22, or since becoming a spouse or common-law partner (if this happened before age 22) or
is financially dependent on a parent since before the age of 22 because of a disability."
 
If you are both PR, either one of you can sponsor your children but you need to be in Canada to sponsor people.