Unless they had some really good H & C reasons for NOT being in Canada then appealing is pointless, it will be refused in the end.
I don't think there is any way you can sponsor them under family class because:
1. It would appear your son is over the age of 19 years now
2. Your son is married and no longer a dependent anyhow.
Is there any other way your son can migrate to Canada on his own merits? Perhaps he is a skilled worker or something similar?
Reading another post you put up, am I to understand this is YOUR wife and YOUR 8yo son? If this is the case, appealing will get you nowhere and is a waste of time and money unless she had some serious H & C reasons WHY she remained back in the home country.
I would just go ahead and file a new sponsorship application for her and your son. It will be quicker and cheaper than an appeal.
Good luck.