This is all very discouraging, given that the OP's sister-in-law was refused a visa even though she appears to have strong ties to her home country through her employment and property ownership, but not so strong when it comes to 'family' ties. It seems like the threshhold is set extremely high for anyone trying to visit their loved ones in Canada and you need to have both the financial resources and family ties.
In my friend's case, he applied in December for a visa for his wife's mother in Syria to come for a three-month visit, as she has never met her grandchildren, and her daughter could use some help with child care. The application was rejected, citing insufficient proof of ties to Syria. The family here are Canadian citizens and sent proof of their financial ability to support her during her entire visit and pay her air fare. She has lots of family still in Syria--several siblings and even her own mother who still lives with her (and is dependent on her--which was mentioned in the application as a way of showing she has responsibilites back home). But she is over 60 and retired, hence no employment income and limited funds in her own bank account (I'm not sure, but she may be getting a modest pension and I'm guessing the siblings help with support). My friend has asked if he could re-apply for the visa but I am hesitant to encourage him to do so unless his mother-in-law can come up with some stronger proof of her own financial security. I read somewhere that it's not a good idea for family in Canada to transfer funds to a relative overseas to put in their bank accounts to show sufficient resources, but perhaps someone could comment on that. I'm starting to think this is hopeless, and I'm sure being from a troubled country like Syria doesn't help matters. But any suggestions would be appreciated.