Rail pass type - with kid

I have a query on the type of pass to get.
I am traveling with a young kid(2yrs) who doesn't need to pay on the JR trains. But I want to make sure she has a seat as I'll be taking 2 shinkansen journeys longer than 2hrs. I was told that the green cars(1st class) are usually quite empty while for the normal cars, reservations are usually necessary. We are undecided as to which pass to get cos 3 normal passes (2X28300+1X14150) cost is almost near the cost of 2 green pass(2X37800). Someone suggested us going to the unreserved sections but we are not sure whether if we do that, will we risk missing the trains because it's full.

Can I find out for the below routes, will the trains usually be full & there will be seats in the normal car without reservation?

1) Tokyo-Kyoto Hikari at 9.33am on a Tue in mid May

2) Kyoto - Odawara Hikari at 1230pm on a Thu in mid May

For the other short journeys, doesn't matter whether she gets a seat or not.

Would also like to ask whether in situations where the unreserved section of the normal car is full, is it possible to pay surcharge to be upgraded to the green car or the reserved section on the train(not in advance)?

Would greatly appreciate any advice!

non-reserved seats are in several special cars at the very front or very back of the train. Big electronic signs on the platforms show where these cars are. if you don't have a reserved seat you need to line up by one of the numbers for the non-reserved cars as you will only have a few minutes to jump in a car.
please check
http://www.japanrailpass.net/eng/ and read ALL the pages.."If you have an Ordinary-type JAPAN RAIL PASS and want to use a Green Car seat, you must pay the Green Car charge and the associated limited express or ordinary express charge".This means that you can't pay the difference between normal fare and green car fare but have to pay the full green car fare. At any rate you will not know until the train actually stops whether or not there is a free seat so by that time it is too late to even think about upgrading. Try not to plan a long trip for the day you land and not at rush hour. Get your pass and reserve your first long trip as soon as you arrive, even if you only use your pass for the 1st time 3 days later for example.and don't fret so long in advance.

I think two ordinary rail passes are enough. The hikari 407 starts in Tokyo, so when you are at the platform at 09.13 h or earlier you can queue up in front of one of the entrance doors for non-reserved seats, can enter the empty car and occupy a three seats row. Only in the very unlike event that the train fills up heavily at Tokyo or at the stops of Shinagawa and ShinOsaka ( but the first who entered the train at Tokyo are already leaving at ShinOsaka ( a.s.o. ) it might be friendly if you offer the unpaid kid seat to an elder person standing. So worst what can happen: Train completely full for part of the journey between two stations and people are standing in the aisle. Only then kid might loose its seat, or one of the adults is ready to stand for a while. But again, very unlikely for the whole journey. By the way: Nobody, even very unlikely the conductor, will ask you to make free the kids seats. In opposite, experience that a Japanese will stand to offer his seat to the "visiting foreigner".
Similar for the hikari 416 from Kyoto 12.29 h to Odawara. This train started in ShinOsaka, so you will enter a non-reserved car not completely empty. But as a midday train expect it not to be occupied heavily.
If you opt for reservation, this can become more difficult: You will get two seats reserved, the JR person will even understand that you want two seats of the three seats row, but you have no quarantee that any other JR clerk at any other JR railway station will not reserve the third place to another person. So my option would be 2 Passes and non-reserved cars.

Sorry, please read that the hikari 407 goes: Tokyo - Shinagawa - ShinYokohama and further. I wrote ShinOsaka instead of ShinYokohama.

thanks for your advice.

I think I will go with 2 rail passes and wait in line early like what Peter suggest.

in the event the unreserve section is full, is it possible to pay the reservation charge on the train and sit in the reserved section instead?

You cannot pay the reservation charge on the train. You need to book at the JR booking office.
We travelled with a rail pass between Osaka and Tokyo in January return and found that we did not need to book to get a seat in the Ordinary Car.

pardon me for asking...If I bought a JR pass, U mean I can reserve seats, say for my next days planned trips ?? Is there any charge for reservation and it is fix charge ?? green car also charge, so what is difference ?? Is there a difference gate for reserve seat & non-reserve seat tickets ?? will I know my seat position at the time of resrevation?? or I need to find myself when boarding,because it mut somewhere ??

Aaron you really need to read the JR pass internet site carefully.at www.japanrailpass.net/. It explains how to reserve seats etc. YOU also NEED to read the section about trains under TRAVEL at the very top of this page. You can reserve seats with your pass from several days in advance to 10 minutes before departure. The reservation is done at the ticket office BEFORE going through the gates to the platforms. Reservation is FREE with the JR pass. it is only done for long distance trains. OBVIOUSLY if you reserve a seat your ticket will SHOW the car number and the seat number!! there are no special gates for reserved and non-reserved! Once you go through the main gates to all the platforms you will have to find the platform for your train (there are lots of platforms in big stations, most are for normal trains and others are for shinkansen. sometimes these 2 types of trains have different entrance gates. All the signs are in Romanji (latin alphabet). On the platform for your train big signs will tell you about non-reserved cars, how many there are, where they are located in that train. all other cars are reserved. make sure that you line up on the platform by the number matching your car number if you have a reserved seat. Green cars are much more expensive than normal ones and only a bit wider and with more space for the feet.

thank you, auntie bert.....