A trick I use to make sure I have the space to bring a room into an existing lots to transfer stuff like that is to make it a basement room. I don't know about you, but I've never started on a lot where the basement level was very full if there even is a basement level to the lot at all.
Just a suggestion for if you ever do this again and want an alternative method. The Household Inventory is how I normally do it though, works great. I mostly only use the room-to-gallery approach if I'm transferring a household to a whole new save game.
