My dts are just over a year old and have never yet slept through. They are on three good meals a day, I have just introduced a bottle of formula at bedtime (as yet no effect). Until then they were breastfed, and still are when they wake in the night, as this has been the way for me to get the most sleep. Some nights it is horrific, with a seemingly continuos relay of feeding. Other nights it seems to be each waking every 3 hours or so, but thankfully not at the same time. I still sleep in the same room as the babies, as I don't want to have to be fully awake and walking from one room to another to feed and then going back to my bed, only to be disturbed 30 mins later by the next call!
I realise that I am going to have to bite the bullet at some point to get this sorted out, because I'm getting a bit down about it now. We have space to separate the twins and have their cots in separate rooms, but I felt very strongly that they should be together early on, and now it seems a bit mean to separate them (it doesn't matter how bad my night has been, I always smile when I see them beaming at each other in the morning).
I'm just interested to know what others did in this situation.