It may frustrate them a bit, I'm sure. But many do it. I do it. I hate to, but I do. Otherwise you would have too many birds. You are actually taking better care of the birds you already have by not letting them get over crowded. So just explain to them that you are doing it for them. That's what I do. LOL. I don't remove them till they are tired of sitting on them and either kick them out, or just stop sitting on them. Eventually, they may lay eggs right beside the fake ones, so you have to keep an eye on them. They're sneaky that way. Let them sit on them as long as they want. Some of mine sit way longer than 20 days. Guess they just don't want to give up hope. But at least it is giving the female a break from laying while they do that.