Knowing Larian is not amused modding their games
I only want to make an announcement that it is possible
to insert objects into the game.

First approach was to move a bed, a table. The collision shapes did rest on their old position.
I was too lazy to investigate on this and focussed on chests:

[Linked Image]

The next step was to insert new (i.e. cloned) ones:

[Linked Image]

The disadvantage is that you'll have to start a new game because interactive objects are stored in the savegames as soon as you entered the region where they reside.