We had that problem too with our pack of Yorkies. It seems one would wake the other, etc.
It took a week or so and they learned what the words "Night-night" meant. When we say it they know it's time to go to sleep.
Mine still get up at 4:30 but that's when I get up as I am at work by 6:00 am so it's not a big deal but...if they wake at 2:00 am - it's still NIGHT-NIGHT TIME!!!
