Hi there and
to Talk Budgies!
I'm sorry for the situation you currently find yourself in. It never is a good idea to do colony breeding or anything similar to that for the reasons you've discovered. However, I'm glad that you moved the pair and their eggs indoors; that is a much better situation.
You've been given great advice. I hope that the little chick pulls through
Be sure to look through the links provided above, which include the forum's many Budgie Articles and "stickies" (threads "stuck" to the top of each subform for easy reference) to stay up to date on all the best practices for caring for budgies. If you have any questions after reading through everything, be sure to ask as we'd love to help!
Please keep us posted on how things progress!