Final answer:
The provided excerpts do not directly reference three brothers or authorities allowing them to stay together, and the specific context is missing, making it impossible to identify an accurate quote without additional information.
Step-by-step explanation:
You've asked to find a quote from chapter 1 that supports the claim that authorities allow the three brothers to stay together as long as they "behave." However, the excerpts provided do not reference the three brothers directly, nor do they mention a specific book or narrative context. Without the proper source material or specific chapter details, I'm unable to pinpoint an exact quote that corresponds to your request. If you can provide the name of the work or further context regarding the brothers and the authorities referenced, I would be able to give a more accurate and helpful response.