All of the above are good suggestions.. make sure "tiny" is warm when/if you supplement feed. Give her as much "mom" time as possible, if needed, hold off bigger brothers for a bit so tiny girl gets alone time.. have big brothers start the process however because she maybe to weak to get the things flowing.. have one of her larger brothers start sucking on a nipple, then, once the milk starts to flow.. pull him off and put her on.. once she has her fill.. there will be enough left for them once mommy gets eating well again and the milk comes in. Mom is always best.. I would feed every two hours at this age.
Giving mom the extra calcium as suggested by the others in the goats milk, the cottage cheese, eggs etc.. she should be doing much better very soon.
-Diana