Hello. So let me make sure I'm understanding you correctly on this. Did you get these eclectus parrots as pets? Or as a breeding pair? It sounds as though you got them with the intent to breed, but are frustrated at this point that they were apparently misrepresented as a potential pair.
So assuming my take is correct, let me ask why you are looking to breed them? Given your questions, I'm fairly certain you aren't an experienced breeder. So that being the case, I suggest that you take the time to do extensive research on breeding and what it takes to do so successfully. You'd be surprised by how many people find themselves completely out of their depth once their birds breed and they find themselves with a clutch of feathered babies. Especially once something unexpected happens.
I suggest you take a good look at the thread in this link before going any further:
http://www.parrotforums.com/breeding-raising-parrots/54987-before-i-start-breed.html Great read. Very informative and puts forth the questions that need to be asked before venturing into the world of breeding.
As for your question about whether you should put a 3rd ekkie into that same cage, that would be a definite no. There is actually a risk factor in having 2 in the same cage, much less 3. Sure, there are pairs of ekkies that get along in the same cage. But there have been cases of a disagreement between 2 ending in bloodshed and even death. Why? Simply because one ekkie has nowhere to which he/she can go to escape the wrath of the other, whereas in nature they would have all the outdoors at their disposal. A 3rd would exponentially increase this risk.
As for their lack of interest in toys, they might never have been exposed to them when they were younger. Some parrots have to be taught to play, believe it or not. And they learn by watching you. So if you make a big show of playing with their toys, it might eventually stimulate their own interest in seeing what's so great about them.
There is also the possibility that the toys you've provided don't necessarily call out to them. Eclectus, for instance, tend to prefer softer woods on their toys. They enjoy the feeling of carving through the softer woods over the harder ones.
And yes, I would remove the nest. Last thing you want is to induce hormonal behavior in a bird who has no outlet for said hormonal surge. If they are not showing interest at this point, there's a good chance that they never will.
And while it's possible that the female may find herself attracted to the younger eclectus a few years into the future, it's equally possible that she'll be just as uninterested in him as she is to her current cage-mate. But either way, as I said, don't house all three together.
