Clan Wolf moved to the Free Worlds League for a reason that I still cannot discern.
They actually moved to the Steiner side of the Steiner-FWL boarder, the Steiner Archon thought that she could use the Wolves in her ambitions to annex the Free Worlds League. Somewhere along the way both sides turned on eachother, and the Wolves managed to annex a good chunk of the Lyran gains in the FWL.
The reasons for this? Well, their original position in the Inner Sphere was lousy. Their worlds were, if Touring the Stars is accurate, economically worthless crapholes. They were surrounded by hostile clans, so expanding is out of the picture for them, and the Steiner Archon was offering free passage.
Out of all the things in the Dark Ages, that is actually one of the few things that -do- make sense.