Family Classで再申請されてはいかがでしょうか?
http://www.cic.gc.ca/english/immigr/ifamily-e.htmlFamily members eligible for sponsorship are:
-spouses
-parents, grandparents
-fiancé(e)s
-dependent children, including adopted children
-children under 19 whom the sponsor intends to adopt
-brothers, sisters, nephews, nieces, or grandchildren who are orphans unmarried and under age 19
-any other relative if the sponsor has none of the above family members either in Canada or abroad.
それでも、何よりも肝心なのが、息子さん一家の意向でしょうね。その意向によっては、Res1さんの意見の方がよろしいかもしれませんね。