There are some closable offshoots of the webway that are connected to Commoragh that might fit the bill a little better. They'd just need to find one with a door big enough to drive a craftworld through!
Kabal of Venomed Dreams
Which is a problem, they are rare and do not cover a lot of ways... that is part of the reason why craftworlds seem to never leave "their" part of the galaxy.
I really prefer the old fluff, before 6th Edition came out, where it had Craftworld Eldar and the Dark Elder far more opposed and lethality pitted against one another. It made so much more sense, since the craftworlders see their Dark Kin as the hanger-on's of those who brought their empire down in the first place.
http://www.lounge.belloflostsouls.net/showthread.php?52423-The-Blood-Pact-Chaos-Homebrew-Supplement&p=472214&viewfull=1#post472214
The latest DE codex still has them viewing craftworlders as naive, arrogant fools who squander their lives with denial and self-sacrifice, and I presume that craftworlders still have an equally bleak outlook on kabalites. I think the key point though is that they still recognise each other as cousins if not siblings and think that individuals of the opposing race can be 'enlightened'.
A bitter civil war is easier to wring peace deals out of than most of the setting. (Even if I do get the impression that it is the very sibling "I want you to hurt badly, but I'm the only one that is allowed to hurt you" deal.)
Kabal of Venomed Dreams