Edalyne If you put the nest back in MAKE SURE THEY HAVE PLENTY OF CALCIUM and vitamin D to absorb the calcium. 2 hens with a nest could (and most likely will) lay a LOT of eggs!! Egg laying takes a lot of calcium out of the layer and energy (watch them sometime laying, it literally looks like a woman in labor... your heart goes out to them, then once the egg is out, they flit about) Anyway, cuttlebone deffinitely, but if you notice even one egg, you'll need to provide more than just a cuttlebone, IMO. I provide eggshells, daily if my hen is laying. And let me tell you she KNOWS when she needs them. I barely have my hand out of the cage and she is flying down to get at those shells. However, calcium is not good if there is no Vitamin D to absorb it. So if they do not get any direct sun light (remember, most newer window block UV rays, so even if they are in front of a sunny window, they still might not be getting the good stuff from the sun) There are calcium supplements out there that usually include the Vitamin D for absorption, among other things, natural such as certain foods. So that is my only warning on that.
As far as the original situation you posted about, I'm glad it worked out... and your husband FINALLY believed that Three Zebra finches just DOESN'T work!!! LOL
I buy Manzanita perches for my birds. They are natural (manzanita tree, or shrubs I think) and they usually have a few different branches off the end, I like the sandblasted ones, but they have natural too. Also, get different thicknesses, as it's good for their feet. (which sometimes the manzanita branches, the ends have a few different thicknesses on them and with the sandblasted they are rough so you are getting the nailtrimming (the roughness kind of files their nails) the different thicknesses for the feet excercise, and a good solid perch so you are getting all you need for their feet care in ONE perchase... (see what I did there? instead of Purchase?, we try to keep a sense of humor around here...

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They are very intimidated, who'm I kidding? Scared crapless of new things in their cage, however Zebras are VERY curious... they can't help themselves! So eventually they will go to that new plant you put in, and peck at it, climb on it (if they can) stand on it, and bite it. They'll start biting and pulling on it... Mine pull my fake plants into their cage all the time!!!
I won't overwhelm you with stuff, as it is a lot, but one big thing, not to forget is that they eat ALL sorts of different foods. Obviously you will have to try different things, but my Zebs' LOVE cucumbers and romaine lettuce, it's really cute, they eat almost perfectly round holes out of the middle of the cucumbers!!! Just know they don't (and shouldn't) only eat seed
Ok, I'm really done, obviously this is just MY two cents, which btw MOST of which I learned by THIS FORUM and all of the amazing people on it! So WELCOME. If you love your finches you have deffinitely come to the right place!! Good luck with your new kids, and FYI, we LOVE pictures around here!!!! So we'd love to see your birds!!! Hope all is going well. Good luck!!!