You mean flowback? As in AA pilots coming to Envoy? Nah. AA did that once back in the mid 00s after 9/11 to prevent furloughs. Hilarity ensued, shenanigans went down like one Captain who would announce to passengers he was "on loan from AA", another who accidentally blew the baggage extinguisher while two rampers were in the cargo hold, etc...

If you are asking if Envoy flows can return to Envoy after flowing..that's also a negative. Much like my anus hole...that's a one way street.