回复：你的小孩是美国公民吗?你把他加进去了吗?

Yes to both. And I also applied for my baby. A few reasons to do so:
1. Benefits for your kids if you have to move to Canada someday later
2. To show your sincere immigration intent to the Canada CIC. They may revoke your immigration visa if they doubt your immigration intent even when landing or just simply reject your application. (if you are just doing it for "backup")
3. It doesn't cost much to add your kids in the application. (No landing fee required for dependent kids.)