HI J.,
I'd say that you are kinda putting the cart in front of the horse on a couple of counts.
First, 2 1/2 year old kids don't decide on adult issues. They aren't capable. Their brains won't be completely built until they are at least 18 years old, and they currently aren't really capable of abstract thought.
On the other hand, their emotions are what run them most of the time.
So, they'll pick up on your feelings and will respond. Mostly, they'll feel scared.
They aren't ready to answer questions much beyond if they want to eat, poop, or play. Anything else will tend to cause them to feel anxious.
Second, this is an adult issue. It's none of your child's business how many kids you want (or don't want).
The adult job is raising the child. Not asking for the child's input on how he or she wants to be raised.
Just think how goofy this could get in the future.
At 13 the average kid is probably all for driving a car, and doing all sorts of things that he or she hasn't a real clue about.
If you begin setting a precedent where your kids actually expect that they are capable of rendering adult decisions, the boundaries between what is adult and what isn't will vanish and you will have your kids arguing you with stuff that is none of their business, and stuff they know nothing about. They'll be telling what they should eat, how much sleep they need, why school is not for them, and all sorts of things.
Good luck!
Tell me how it goes.
R.