Well, in case they don't help you:

Don't enter your private large until it gets autodemolished. This might take a while, since this is on halt currently. Make sure your private large falls at a time when your server is mostly empty. Once the plot is empty move your FC. The previous small FC plot will free up 5 mins later. You buy it as private. Least loss made. Make sure you have the money to buy the plot since the 80% will end up with an NPC first.