Once more JR Pass question

I've done my research and looking for advice. We will be traveling with 5 year old, which generally doesn�t need JR PASS (until 6 years old). We will have 14 days passes for adults and will be staying 5 days in Tokyo, than trip to Hiroshima for 2 days, few more days in Osaka/Kyoto/Nara and back to Tokyo. We will use JR a lot. I think we still should get pass for our kid �Emy understanding is that even she will be allowed to travel for free we can�t reserve seat for her. It would be important especially for longer trips between the cities. Is my understanding correct?

Thanks - ROB

my understanding is that even she will be allowed to travel for free we can�t reserve seat for her.

That's right. But note that most trains have some cars with unreserved seats, which can be used for free by your child. The only risk is that you might not find vacant sets when it is crowded. This risk can be decreased in case you board the train at its first station by arriving on the platform in advance. But if you board a train along the way and it is crowded, you might have to stand.