There is no problem with three. Or four. Even numbers tend to work better, otherwise you risk two becoming really good buddies and one getting left out a lot. You can also have some rivalry and jealousy going on when that happens. (This isn't a problem just with hens; it is the same with boys.) That being said I know people who do it with no problem. It really just depends on the individual birds and their people. You just have to be well versed in flock dynamics and know how to manage them. If you aren't you might have some problems.
I would, however, make sure that at least one was tame. And I would get the next two one at a time, so you don't overwhelm Zoe. It would work best if the next one is tame, actually, and then you can add another wild one or tame one once Zoe is tame. That way the tame one will help you tame Zoe. It will do wonders for her when she can see you playing with the other bird, and the other bird enjoying it. That in and of itself is often enough to tame a budgie, if they have some measure of trust in you to begin with.




