I'm at my wits end...

The twins just wont go to sleep.

Before Max was born they would go to their room at 9pm and be allowed to watch 30 minutes of TV. They would usually fall asleep during that time and then wake up around 8am the next morning. They would have an afternoon nap about 50% of the time.

Since then...aggravation!! The routine got thrown out the window. Between my parents living here for 3 months and a new baby who initially cried from 8p-midnight, they ended up going to bed later and later. What usually happens now is the kids get put to bed about 9p and depending on their behaviour get the 30 minutes of TV. But they don't fall asleep. K will usually fall asleep first around 11p while S sometimes is still wandering around the house at 1am! They will sleep in until 10-11a if I let them. But with school potentially starting this fall I need to get this fixed!

I have tried multiple things
-yelling, screaming, threatening a spanking if they don't stay in bed.
-removal of the TV completely
-forcing an afternoon nap, thinking maybe they were over tired.
-not allowing an afternoon nap.
-waking them up earlier - two days a week S has speech which means we get up at 7a and even on these days they stay up late.
-cutting out dietary stuff
-allowing them to sleep on the floor in my room/not allowing them to sleep in my room
-baths before bed
-moving bedtime up even earlier...ie 8p

Nothing is making a difference. As I type this at 11:30p I can still hear them wander. The TV in their room is off, the lights are off, I have completely ignored them since putting them down at 9:30p. They get up and get a toy or move to the couch...few minutes later back to bed. Also, by the time I wake tomorrow morning, one or both will be in my bed. They share a room, but that can't change. I have no more space to separate them. Toys have always been in their room, but again, unless I just get rid of them, there is nowhere else to put them.

Any ideas...I am tired and the kids need to get back to a normal routine.