Welcome To BYCHello, I have the same issue with broken feathers,white dust, and tiny white flies, chickens have missing feathers underneath their belly between their legs. No Rooster here, the chickens get along with each other. They are eating, drinking and laying eggs. Please HELP!!!
Can you please post photos of your birds, the tiny white flies, etc.?
Where are you located in the world?
Tiny white "flies" are those crawling on the birds themselves/on the skin? Sounds like you may be seeing Lice. Permethrin poultry dust can be found at most feed stores, dust your birds once a week for a few weeks to get rid of the bugs.