I see a couple of issues that need to be addressed. The child isn't getting enough sleep and therefore, neither are the parents! First, they need to know that he doesn't need the extra feedings at night. Check with their pediatrican and make sure he is getting balanced meals during the day. The extra milk is likely not needed if he is getting enough nutrients during the day. So basically, he doesn't the bottles in the middle of the night. It is tough, but I believe the best thing to do is to let him cry it out when he wakes up in the middle of the night. This won't last long and he'll learn to put himself back to sleep without a bottle. He can do this and so can they! They just have to have the will power! It is tough, but it shouldn't last too long. He desperately needs his sleep and it doesn't sound like he is getting enough of it--and then obviously, neither are the parents.
This leads me to my second point. (No, it is not that he should be off the bottle altogether. My daughter wasn't ready to give up her bottle until 18 months, but she ONLY got a bottle one time at night and then we completely transitioned to the sippy cup. If the baby gets a bottle at other times during the day, they need to start working on the sippy cup now and transition to it). My second point is that this baby is not getting enough sleep! Children his age need 12-14 hours of sleep at night. If he's not going to bed until 10pm and then he gets up at 2 and again at 6:30, the parents are not giving this baby enough sleep!! He really needs to get to bed earlier. Most experts say that babies his age should be in bed by 7:30 or 8:00. My daughter goes to bed at 8 and doesn't get up until 7 EVERY DAY! It is hard to get them on a schedule, but it is the BEST thing for the child and the parents! The parents will get a little extra time at night and then the child will be getting the sleep he needs. It isn't easy to get your baby on a schedule, but it sounds like it is overdue, considering everyone is so tired! Some working parents don't want to do this because they don't get to see enough of their children if they go to bed early. Being a working mom myself, I can sympathize with this, but keeping the baby up is just being selfish. The baby needs his sleep!
Parenting is not an easy job. But, there are some things that we have to do and I am a really firm believer in schedules. My daughter sleeps 11 hours at night and then takes a 2-3 hour nap every day. She wasn't always this way. When she was younger, I didn't have her on the schedule she is on now. Someone gave me all of the advice I am trying to give and I tried it and it worked! Now, pregnant with my second child, I will make sure to follow some sort of schedule MUCH earlier because it makes for a happier family altogether. It is only hard at the beginning and then it makes life so much easier for everyone. Good luck to your daughter!!