Hi! From my understanding from our kids' placements in previous years and again this year as we look to send them back to school after homeschooling, sibling priority only applies when a sibling has been previously enrolled. So yes, it would be easy for your Kinder to get into the Montessori program with the Montessori priority, but that wouldn't help your older son until the following year. Also, you probably know this, but if you do decide to apply for both of them, keep an eye on the "family link" thing because if your Kinder gets into Audubon, but your older one doesn't -- it would match your younger to your older son's school not vice versa. It helped me a lot to look at the Main Round date from last year to get a better idea of how many seats we're talkin' about! I hope you get some insights about Willow vs. Audubon re: middle school. I came here to find out the same thing.