Lesley you must be a fish whisperer, at least with the wrasses
You have a sixline and a fairy wrasse in together? Were they introduced around the same time? I never saw it but, I kind of suspect my sixline of harrassing the Scotts. The sixline, I've had for about a year and a half, has always been very friendly to everyone except the royal gramma and that was just when he strayed into it's territory and they would face off and posture before going about their business. I introduced a mandarin a couple months ago and I thought my sixline was going to stress the thing to death. He chased it up to a corner and kept it corraled there for days.
Toytek - a tang and a sixline wrasse shouldn't have any problem with each other. Most community fish tend to be aggressive to other fish they find similar to themselves. There are always exceptions to the rule. ( Although, my sixline must be delusional if he thinks he looks like a mandarin
) I think fish compatablilty charts are helpful. A good book or I've even seen them online.