Well, for example, I bought a Small house for personal use with 2.38. A week later I had buyer's remorse at the size/location of the thing and was eyeing up a Medium in Mist, but I didn't want to lose out on the entire 4.5M I sunk into the small. Small houses on my server were sold out within 10 minutes of the patch, so they were incredibly high in demand, so I put up a PF selling the relinquish for 2M (including the house permit which I believe was 450k) and a small FC decided to go for it. We met at the plot, I demolished the empty house and got the permit back, they handed me 2M, I handed them the house permit, they paid max price for the land, used my old permit to build their house, and that was that.

Yes, if your FC is ready to move on, everyone has to demolish their private room and remove their chocobo.