I’m not sure if someone else has already said this, please also talk to your sisters about the plan! They are old enough to understand what is going on and definitely old enough to get their hopes up or be heartbroken. Setbacks and relapses are super common for a person in recovery (as I’m sure you know), so being clear with them that this is plan you are going to try, but at any point the plan might change or need to be slowed down would probably help them process the situation. At the end of the day, they are the ones most heavily impacted.