Travelling in a group of 4 (2 adults 2 kids) and we only need to check in 1 bag. Is it possible to book with 1 Blue Plus and the other 3 as Blue?

Or is it better to book all 4 as "Blue" and pay the checked bag fee?

Or should I make 2 separate bookings - 1st booking with 1 Blue Plus and 2nd booking with 3 Blue?