Thanks for the detailed explanation!

So I booked with 3 adults and got emailed promptly within 2 days from the hotel with the following info.

"Thank you very much for choosing at Conrad Tokyo.

In regards to your reservation, as redemption stay is only covered for two adults, therefore third guest needs an extra charge, it will cost JPY 7,500 (exclusive of tax and service charge) per night and includes the rollaway bed.

We have arranged it at this moment. if you do not need to arrange it, please let us know it before check in.

For your reference, please find the dimension of our beds;
Twin Bed : 1.4 M Width x 2.03M Length
Extra Bed : 1.2 M Width x 2.03M Length"

I'm going to to let them know about 2nd child just to make sure it's ok.

Bottom line looks like for my award stay, I'll be paying the 3rd person/rollaway fee (which is perfect for us, as older one would want own bed). And we'll just have to keep our fingers crossed on EL fees for the kids. If they want kids fees for EL access, might just decline. I believe there's still free breakfast I believe?