What exactly is a JFRV?

Article 25 of the Immigration Act indicates that you can. However, certain residence purposes are excluded. Residence periods on an ARC issued on the basis of studying or blue collar labor are explicitly excluded. Article 25, Immigration Act

Please note that JFRV is not a proper legal term in the Immigration Act. What you refer to as “JFRV” is an ordinary ARC with the purpose of joining family.