I don't know if this helps, but my wife is a nervous flyer, so I usually put her in a row not near us and will fly with the two kids son 6 and daughter 8. This typically means we are a, c and d. My daughter will usually sit in d, so I can look after my younger son. With the divide in CE, my daughter never really feels like she is sat alone and can just turn left if she needs me. I also think this is the best option, if it turns out the same for you, since it means you can monitor them and order for them as opposed to leaving them sat next to each other and having the difficulties of moving things around, finding iPad or one or the other coming to visit them if you are 2x2.

Anyhow hope it all gets sorted,