Help me put up an invisible wall

In order to buy furniture for our sitting room (at the bottom of the plans) I think I need to put up some invisible walls in between the dining room and sitting. Where do you think we should put our invisible wall? At the bottom of the double doors (and therefore have the sitting room smaller) or at top (making the sitting room bigger)?

Invisible wall at the top of the double doors

Or

Ivisible wall at the bottom of the double doors

B