Get everyone you know in the Barren Hills to mention rescuing captured prisoners when you fight Dark Elves (ie, "Though victory on the field was denied us, our flanking maneuver worked, and several hundred civilians were whisked from the enemy camp in the midst of the battle and are now on their way to safety with us.") This includes other players you know of other races - (ie, "We fought the Druchii fiercely...during the battle, more than a score of humans broke free of their prison and fled the field; the Druchii were too busy with us to pursue them.")
For me, I've concluded that a local clan of Skaven really wants my general hunting for the Crown instead of battling Druchii to rescue prisoners. For this reason, I keep mentioning how the Skaven appear to be alerting my forces when the Druchii are near and leading us to them whenever they can - the rats figure, the sooner we deal with the Druchii, the sooner we can get back to finding the Crown. It fits with what they're doing this campaign (and helps me justify the fact that half my opponents play Dark Elves...)
In my last report (in keeping with the "pigeons and road wardens" communication method), Earl Jodas was alerted by a pigeon that was thrown against his tent. The bird was dead, but a semi-literate Skaven had tried to write out a warning of Druchii nearby. It was enough, we fought a battle, and numerous prisoners were rescued.
Coincidentally, my dwarven neighbors (figuring that they'd rather the Empire be rescuing prisoners than hunting for the Crown) have refused any aid against the Druchii whatsoever. It's quite insulting, really. But that's just me.
Just a few thoughts, maybe some inspiration in there. Our river campaign this coming week should help us considerably with rescuing and securing the helpless and innocent...mention the destruction of Druchii ships "before landing," etc. That should put a blow to their plans!