Actually I want to both extend her stay and change her visa to a multiple one. I guess I dont have to submit both applications (extend - to CPC-Vegreville and a new multiple one - to CIC in US) b/c they're somehow in conflict. I am really confused now.
So, your help is truly appreciated!
You can apply for a new multiple entry visitor visa now but she would have to leave Canada as soon as her approved visit is over (usually 6 months after arrival). And even if she did have a multiple entry visa, she can not come back too soon after leaving the country. If you applied for an extension of the visit, the average processing time is now 79 days, but there is no guarantee either way that the multiple entry visa application or the extension request would be granted. The request for extension would buy you a little more time though.