Originally Posted by
UKtravelbear
If I've understood you correctly I would suggest this
Make a single booking for you and the kids
Make a separate avois booking for your wife's flights in Club for the same flight outbound and her different return
On the outbound leg just after boarding do a seat swap with your wife so you'll be in Club and she'll sit in your seat in economy with the kids. Just mention this to the crew so they are aware.
Great idea

I did not think about this. Only difference here is that i plan to UUA from W to C for myself. So all our tickets are bought in W class. But then I just upgrade my wife single ticket from LHR from W to C with Avios and take the seat myself. Then no need to split my ticket with the children
Just for my curiosity. If I split my PNR, would the other people (children) in my same PNR loose their seat assignments?