Wally to summerise the other thread.
Previously if you rolled over your insurance on the renewal price then you kept the original terms and conditions, if you felt this price was too hefty then canceled and took out a new policy the 4K limit on any individual item was reduced to 2K and i am unsure if bikes were covered in that.
From your next renewal there will be a policy update to align all policys with the lower individual item limit, however you can still list the bikes as individual items at an additional expense.
OP, i’d recommend going for 2 or 3 anchor points and chains and locking the bikes in pairs. One thing i have found since locking mine up is it is a PITA getting to the bike at the back of the pile once they are all locked together.
A 16mm chain is a BIG chain, it will also be very heavy and if constantly being moved over delicate bike parts or frmaes may damage them if you are clumsy. 13mm is what i use and it is a big chin in comparison to any you will see in a bike shop. You could get a much more practical set up with 2 or 3 of the 13mm chain, lock, anchor packages rather than 1 long 16mm chain, lock, anchor deal.