Hi there and
to the forums!
Tinker is a beautiful girl!
Also, as a point of interest, rainbow is used only to describe a very specific set of mutations; if she's also spangle than most likely her mutation is sky blue greywing yellowface II opaline spangle
Of course, if you have any photos taken in natural light of her, we can help confirm
Also, it's inadvisable to keep three budgies housed together, especially when they are mixed genders, as when they are in condition, the males may fight over the female. Of course, this doesn't always happen, but it's important to keep an eye on them, do all you can to discourage breeding, and have a spare cage on hand just in case
To familiarize yourself with the forums, be sure to read through all of the many articles and stickies that we have here! If you have any questions after reading through everything, be sure to ask as we'd love to help.
We would love to see more of little girl (and your other budgies) when you get a chance.