Honestly, I would never want to take my kids to WDW when they were 2. But that's me. Neither Dh or I wanted to deal with the hassle. A lot of people on here will tell you how they did it, and had a great time. But many people on these boards go to Disney frequently. I don't. (I'm hoping to go a bit more often, now that my kids are a little older..) If you go every year or two, it's not a huge deal to have to leave a park early because you've done it before, or know you will do it again soon.
I think you need to ask yourself a few things. Is this a once in a lifetime, or once in a long while trip? If the conversation is going to be something like this:
your child in 10 years: "Mom are we ever going to go to Disney?"
You: "Yes, we did when you were two, honey. You loved it!"
Your child: "I don't remember."
You: "Let me go get the pictures."
...then I personally wouldn't recommend it. If you plan on going more often, then go for it. You won't be stressing about missing things. Also you said you were planning a big reunion. Do you have a choice? Does it have to be at this time? Can you delay? If you have to do it then, you'll be fine. I don't think taking a two year old is bad. There are some nice things to enjoy with little ones that don't cut it with older children. However, you need to realize you'll probably have to leave parks or restaurants or whatever you might be doing to feed, or settle restlessness, or take a nap etc. If you plan to go with the flow, you won't have a problem. But if you were planning on hitting the parks hard and trying to do "everything", you might be frustrated. (It's not that you won't be able to ride ride that your kids are too young for, as there is rider swap. It's just that there are so many things a 2 year old will need to interupt, while something else is going on.)
I would say try to work the plans around your situation, what's best for your family. And if it's not ideal, considering you're working with a lot of other family members, then work your situation around the plans so that everyone will have a peaceful, enjoyable time.