Welcome to car-seat.org. I hope we can help.
I have an 03 Odyssey, same body style as yours.
Do you have extra tether anchors retrofitted for the 3rd row? That will give maximum flexibility.
I don't think you're going to be able to not use a Radian for the 3rd row. Why won't she use one? You won't need to use a Bubblebum.
My initial thoughts are:
3rd row: Frontier (5 year old) / rear-facing Radian (1 year old) / forward-facing Radian (4 year old) --> load the 1 year old through the hatch if needed.
The Radian won't install rear-facing on the outer seats of the 3rd row because of the hard plastic in the hinge but it goes in nicely in the middle.
2nd row: shift the passenger's side captain's chair to the middle leaving the aisle to the 3rd row on the side instead of having to squeeze through the middle. Put the baby's infant seat on that side installed with lower anchors so you don't have the seat belt awkwardly in the way. You can also slide the whole seat forward if needed while the infant seat is installed. Put the 7 year old on the driver's side captain's chair in a high back. The Monterey works nicely, as does the Parkway. Probably others too but that's what I use.
Buckling a booster is going to be extremely difficult in the 3rd row which is why I would suggest leaving the kids in that row harnessed as long as possible. It doesn't work to have a booster on the 2nd row passenger side captain's chair as the belt fit is terrible and the shoulder belt gets hung up and won't retract or lay flat in a belt guide of a high back booster, and the belt gets in the way of access to the 3rd row by blocking the aisle.
