IF they do get in touch, and start demanding it, its worth seeing if you can reach a deal where by the have a 'degree' or censorship/control to request (read as demand) you change things. Be aware if you link to their official site they will know about your site the second someone clicks the link, but inline with the above they may request a link to the mainsite and maybe the management.
I've heard of a few people who have done this, its mostly been cutting out gossip and dodgey photos.
Make sure your clear its not their actual site too, this used to be the case where being a .org.uk or .info was clear but then pinder/marsh ended up with .info and .biz I think because Dave Reed was kinda slow when he was creating them, so now the extention is nearly irrelevant.
100% Unofficial Fan Site seems to the consensus on wording. They make it like a Stamp effect, you like an approval stamp that says
100% (large print stretched to the same size as unofficial)
Unofficial (small)
Fan Site (same as above)
and stamp it on your banner, images and randomly around the site, fan's are almost immune to this and assume its a 'gimmick' almost.
If your not too bothered with simply handing the domain over then no drs no foul, just make sure you can be contacted via the site clearly, and first step in the procedure will be to contact you NOT DRS you, so its all good.