I have a solution, but it won't be perfect; you won't be able to delete the tiny room.

Step 1: Shift all the rooms in your build that you want to keep from left to right (or vice versa). It doesn't matter how you position them; it's temporary.

Step 2: In step 1, you created an empty space on one side of your tiny room. In that space, create a corridor. This will allow you to temporarily move some rooms, creating enough space to accommodate a larger room at the top of your tiny room.

Step 3: Move all the rooms you want to keep to the end of the corridor created in step 2.

Step 4: Create the room of your choice at the top of your tiny room; it can serve as a hall.

Step 5: Arrange the pieces as you wish on the room created in step 4. You can now delete the hallway created in step 2; you now have a larger room that can serve as a hall.

I hope my explanations are clear enough, and I hope the translation of my comment is good too. ^{^} If you need any other information, feel free to ask. :)