You can add liverock, but be prepared to sacrifice it if you find disease. I.e. you may need to treat the tank with copper = kills everything in liverock, causing a massive spike. You may need to use an anti-bacterial treatment = kills the bacteria in the liverock, causing a massive spike.
For a wormer, you can treat in a few hours in a bucket, so do that rather than in the tank.
However, if you go down the Chloroquine Phosphate route (as I plan to in the next few days), then you can leave liverock in with that. It doesn't kill the bacteria or the worms in the rock. I will also treat with Sera Tremazol to worm the fish in a bucket, and if I see visible parasites, I'll do freshwater (pH adjusted) dips in a bucket.
Watch out tonight, after lights down, for the cocoon around the wrasse. I used to have a sixline that did it. It's cool to see.