i got rid of my paired black and whites to get 2 juvi true percs, that have now paired up, about 8 months ago. i had the same problem as you where they wouldnt go near my rose anenome and just stayed by the glass in the corner so i got annoyed real fast. i evently just caught one and pushed it into the rose hoping it would realize it is capable to do this. since they always followed each other, the other one just followed right behind into the rose. they do not leave either rose (since then my rose/roses have split 4 times!!) except to get food.
by the way dont really recommend this just in case bad things happen but it just worked for me and thought id let you know and you can think about it and weigh the risks.