I obviously havent read the baby wisperer for a while...! And it isnt really for twins as such, and i found her twin routine example a bit rubbish, so i made up my own. But in fact that is what she is getting at. Use the babies own natural routine to kind of establish one that works for you. For instance their is no point waking them up at 7am to feed or whatever if they are happily sleeping then. Essentially what the baby wisperer advocates is that the baby's cry is just communication. Different cries for different things, so dont rush to them every time they peep, work out what they want first. But i digress, alot of it is more relevant for establishing a routine with newborns. The situation you have is you've inadvertantly established a routine of them waking in the night, crying, you come in something happens, ie you sooth or offer a bottle and they fall back to sleep, only to be repeated again in an hour and a half. Exhausting!
But you cant really blame them for this, so you have to re-educate them gradually. I wouldnt offer any bottles of anything during the night. Make sure they have ahd plenty to drink before bed. Do the bedtime routine as described by twinmam ( i know its boring to be doing the same thing every day at the same time and its restrictive of youre life but it makes them easier to manage. I persevered with putting mine down for naps for years and they only gave them up when they started school! so it works) the same order every night, getting calmer and quieter as you approach the bed time. Kids love to know what is coming next and it signals to them what is expected. I had a mobile over each cot and toys and books in the cot which i put in after they went to sleep each night, which they would play with in the night or in the morning when they woke which can give you another 30 mins in morning. They cry in night?....let them cry for a full 5 mins. Then go in, you are absolutely doing the right thing not picking them up. Try to soothe ideally without touching and leave the room. And repeat. The first few nights it may be worse for you, but within a few nights hopefully the will be able to put themselves back to sleep. Then you can work up to 10 mins. I dont say this lightly, but if you are really desperate for a nights sleep, you could try medised or somthing similar just to get them to sleep through, then you can regain your strength.
I know this approach works as i had them sleeping through (11-7) at 14 weeks. They were fine unless they were ill. Then we got complacent. One night the best sleeper (12 months) was ill, so we took him downstairs with us, made a fuss of him, medicine, drinks etc. Then put him back to bed. That one night ruined 12 months of training and for the next week he woke every night, crying, i guess wanting the same treatment. So we had to let him cry, not go in and he settled himself.
Getting them sleeping thru is a great step as then you'll enjoy them more as you will be less tired. Then if can get them to nap quite a bit you will have more time to yourself during the day. Which is why i persevered with the lunch time nap til mine were 4...i needed the down time .
Always remember a childs demand for attention is like the black hole of calcutta....never ending and never enough!!! You are in charge! Go get em girl!