Twin Apraxia...Help!

I have 3 1/2 year old twin boys. I was always concerned about their speech because they never babbled or even tried to talk. At their two year check-up the doctor finally referred them for a hearing and speech evaluation. They did have slight hearing loss due to the constant ear infections, and had tubes put in. The speech evaluation went as expected. I heard the same story that I had been hearing from the doctors, that they are premature, twin boys and they have a lot going against them. They started weekly therapy and after a year, not much improvement. At 3 they got a new therapist that diagnosed them with apraxia. They needed therapy at least four days a week but our insurance would only do one, since then our insurance will not cover therapy because they consider it developmental delay and not needed. Since then, I have been in contact with the school district trying to go that route, but it has been slow. The school district also only covers therapy during the school year and not summers. Currently, I am taking what I learned watching therapy to give them therapy at home. They actually have slightly improved since I started working with them. I haven't pushed sign language on them, but they have come up with their own signs to show me things. They also innotate words by grunting them so they often sound like the word. The boys say less than 10 words each and even then, I have to keep asking them to say it. One of them says bye bye on his own, but besides that they don't even try to say the words they know without being prompted. Not only is there the battle with talking, but potty training has been a nightmare. The boys also have a sister that is 17 months older than them. She has never had any delays and actually can communicate rather well with them. She is currently going to a church preschool 5 days a week for 3 hours each day. The preschool has a speech therapist through the school district that comes in multiple times a week. I have considered putting the twins in the school next year and putting them in different classes, hoping it will push them a little more without them having each other to depend on. One is more outgoing and also communicates better than the one that is more shy and quiet. Would this be a good idea to try this? I have not tried music therapy or supplements yet, but while researching apraxia and supplements ran across this website. I am definately going to try music and supplements to see if it helps. The website is very encouraging for the desperate parents that don't understand apraxia.