Hello ArnStran,
the correct way to do this is to export from source VRF VRF-A with both RT set
for example using a route-map as export-map
route-map myexport permit 10
match ....
set extcommunity RT 65001:1200 65002:1000 additive
ip vrf VRF-A
export-map myexport
you cannot re-export from VRFB to VRFC to avoid possible routing loops
Hope to help
Giuseppe