"we have 4yr old twin girls (they sleep in the same room)
within the past couple months one of them wakes up between 1:30am - 4:30 am just to "play" with her toys
she throws a temper tantrum every time we tell her to go back to sleep because it's not time to wake up yet
we have even told her that it's time to wake up when the sun comes up but that doesn't work
we're all tired and frustrated...HELP!!!"
Just awful. I don't have twins, but I have two kids who share a bedroom, and it just makes you want to yank your brain out through your ear when one of them wakes the other one up, especially on purpose.
I don't know if there's any way to stop your daughter (I read the question as it being one of the girls waking up consistently, not the two of them taking turns waking) from waking up, and am guessing that it's a phase she's going through. My suspicion is that if you stopped caring about it she'd get bored and go back to sleep, and after a few nights of this would stop waking up.
So that means the question is how you can stop her from waking her sister. If you could stop her from waking her sister, then it really wouldn't matter if she woke up to play with her toys, because the other three of your could stay asleep. (And if the other three of you stayed asleep she might give up and go to sleep herself from boredom.)
I think there has to be another room involved in this somehow. Either you could separate them for sleep, or make the waking sister go into another room silently to play with the toys. I wouldn't want to have to deal with switching the beds and sleep, so I'd choose to make a rule about going into another room to play. But that's obviously me, and you might want to go the other way. I think if you did make her go into another room (assuming you feel it's safe to do this--my older son could have been trusted not to get into any trouble in the middle of the night, but not all kids could be, and I predict his brother won't be at that age) you'd find her asleep on the floor in the morning.
If this is making your stomach turn because you just can't see separating them or letting her be alone in a room awake in the middle of the night, we're going to have to go back to the drawing board. As you all have figured out, I tend to look for the thing that seems the most direct, but there are often tricks that I'm just not seeing. So does anyone have any suggestions for Cathy? And if you can come up with a way to get a four-year-old to obey we'll all send you chocolate and beer.