windows and doors to cut two walls

[JCJordan2]

I have a 6 story apartment building renovation. The walls will remain but the exterior skin will be replaced. I created stud walls with sheathing and finishes for each floor. I created exterior finishes for each floor and made the walls touch in plan. The existing windows now do not cut through both the stud wall and the exterior finish. How can I make this happen for existing and when I change the exterior finish in the new construction? I separated the exterior from the interior because the exterior skin will change from one material to possibly two materials but the wall construction will remain the same and in tact. New windows will go in place of the existing windows. In the attached pics, one is the plan and the exterior skin is highlighted. The other is the elevation showing that the windows do not show cutting through.

How can I get the windows to cut through both the interior wall and exterior skin at the same time? What is the best way? All help and info is greatly appreciated. 

[Karol_Piroska · Accepted solution]

try the join tool to join walls. The window will then cut through both.

[ToanDN · Accepted solution]

@JCJordan2

Simply join the existing stud walls with the new exterior skin per @Karol_Piroska suggestion and the existing windows will cut through both of them.  The walls don't even need to touch.