Pure Pursuit, the Voyagers are not 'ours' to modify! They already cost MoD more than £1M
per day for the AirTanker PFI AAR service, so Lord knows what contract penalties would apply if MoD suddenly woke up to the fact that quite a few RAF aircraft would benefit from such a modification.
The K2s would seem the obvious candidates for such modification though. Training boom operators and maintaining their currency might be a problem though, given that the Voyager doesn't have a UARRSI...
So no mutual AAR trips, unlike the Victor or the VC10K.