Believe it or not... this conversation has has re-inspired me to try to introduce them to the nem again.... I moved the rock (temporarily) closer to them ... right under the frogspawn and she has ventured into it... she is now jumping back and forth from one to another...... I will leave it there for a few hours and then move the nem back to the front of the tank.... I really don't want it moving onto the reef.
Hopefully they will tag along for the short ride and stay in the digs. If not I will try the mirror trick.
Thanks for the inspiration Doug.....
Cheers
Lawrence