If he won't stay lying down and sleep, perhaps you could try to persuade him to sit down and play quietly or look at some books for a while? Or sit and watch a DVD? Or would he maybe lie down with you and have a quiet chat, cuddle etc? I know it's not the same as a sleep, but at least he'd get some sort of down time. What's Charlie like with settling in the evening? As a last resort, you could try just putting him down an hour earlier at night, and then do whatever you can so that Toby doesn't disturb him so much.