you might be able to request bulkhead bassinet seat and move out the current person there assuming they have no infant.

assuming your lap child still fits into the bassinet it is advisable for such a long flight!

in terms of seats, if you get the 2 middle seats, you should know you cannot easily move between the 2 seats. It has a high middle partition. The easiest would be to get a middle seat and a directly across window seat so you can help each other out. Since you have 3 adults, it is no harm to get 2 middle seats together and one window in the same row. But if only 2 adults i would recommend 1 middle and 1 window that is next to each other.