Thanks for your comments, they were helpful. I thought I would update this for others who may be interested. Just before my first leg (over 72 hours prior actually), our seats were automatically assigned and changed to "Restricted", meaning even if I wanted to pay to change it I couldn't. The algorithm automatically placed us row 46A, B and C and 47 A, B and C. Really happy with this as I have flown the A380 many times and always wanted windows seats infront of the engine but always ended up overwing (funny story on Qatar I once booked around row 45 and got moved to a wing seat for "load balancing reasons"). Also, happy that the algorithm put us on 3 / 3 splits, rather than 6 across one row.

On my second leg, the seat assignment did not automatically update at the same time and I could change it as much as I wanted (with payment of course). However, today with just over 48 hours remaining (and a day later), that also auto-assigned seats which are overwing on the 777 but across one row, row 20A, B, C, D, E and F. Interestingly, it displays the seat assignment different as it says "20A / Regular Seat" and I can still change it, where as the first leg just shows "46A Restricted". Not sure what these mean but the implication is that I will still be able to change both at online check-in.

Our online check-in is still yet to open (opens later today as the 48 hour time slot is not yet there).

We are also travelling with 1 child and 5 adults, not sure if that affects the algorithm.

I did enter my Skywards number which has a seat preference of "Window seat", but this was not respected by the algorithm (I guess when travelling in a group it just focuses on seating everyone together as first and only priority).

Hope that helps anyone else interested.