seperate surface on wall fail

[Anonymous]

Dear Colleagues,

we have modeled the subdivision of the surface design using the tool "divide surface" on outer layer wall, this worked well for some time. 
The problem happening now is when we want to place a new window or making any adjustment to the wall, the subdivision lines dissappear. There is no any kind of warning attached to the wall element.
Are you guys familiar with this kind of problem?

best wishes
Mostafa

[Anonymous]

Try using the join tool from the modify tab and join the window to the wall that isn't getting cut. If its not the join tool its the cut tool.

[Anonymous]

we have tried both ways.
after the cut was made, the subdivision lines dissappears and we want to keep them in coming planning phases

[barthbradley]

Check your Part Visibility under view properties. Does it say Show Both or Show Parts? Also, Join Geometry doesn't work with Divided Parts.  Use Merge Parts for this.