Don't know if this will help but there is a character hotline. Go up to any cast member who has access to a phone (guest relations, stores, etc...) and you can ask if "x" will be in the parks today and where. You don't have to be in the same park. The hotline is the same everywhere so a cast member in the Magic Kingdon can tell you where someone will be even if they will only be at Epcot that day.
Although what's been said above is true; it is really rare to see all the dwarves together so this may not work for you but it's worth a try and that way you won't have to wonder if you missed them.
I did this for Mushu a few years ago and found him! Apparently the characters for the day are notset in stone though. I spent a lot of time being told "nope not yet" check back in 2 hours. So you may have to check in when you get to the parks and then continue to check in throughout the day.
Who knows, if you ask enough, and get some kind strangers to ask too then maybe they will give in and produce the dwarfs!