SusanC

Just what Mark said - make an architectural block of the cabinets you want to combine and you will be able to place them as one unit.
Select the cabinets with labels turned on. Block the cabinets by using the "architectural block" tool. Add the architectural block to the User Library using the "add to library" tool.  Schedule will report the cabinets as individual. If you need to move the cabinets individually in the future, just "unblock" them.  
 

If you're in hurry, another option is to use the Wolf ceiling hood which is flush mount and looks similar to the Nuvola 90 when it is installed up in the ceiling.  You can find it in Chief's Wolf Cooking catalog.  If you need to have your schedule populate correctly, you can just go into the dialog box for this hood and change the name, the specs, etc.  
Good luck!

I think you are just missing a check box in the dimensions.  If you double click on one of those dimension strings to open the dialog box, look for "Options" to see if you've checked "Display Gaps Between Cabinet Face Items".  
If that is the solution for you, you'll need to go into your defaults and check that box so all of your dimensions now work that way going forward.  

Just turn on the layer for "Cabinets, Module Lines" and you will see the lines between the cabinets again.  

If I'm understanding correctly, you are trying to fit an oven into a 600mm, or 23 5/8" cabinet?  
Easiest way I know of to do this:
Make the cabinet wider than needed.  I made a 30" wide cabinet. I selected a Wolf 30" oven and inserted into cabinet.  Double click on the cabinet to open up the dialog box.  See attachment showing oven highlighted.   While dialog box is open, click on Front/Sides/Back tab. In the "Face Items" section, click on "Appliance". Look a little further down and you will see you Appliance/Door/Drawer  with the option to Specify, Edit, or Clear.  Click on "Edit".   Now a dialog box pops open to allow you to adjust the manufacturer's appliance to any size you need.  Once done, click "Ok".  See attachment showing 2 dialog boxes open. Now go up to "General" tab on far left and size the cabinet down to 600mm.  Click "Ok" and you will now have an appliance that fits into your cabinet.  See third attachment with oven and cabinet size adjusted down. If you need a quick fix for now without making any adjustments to cabinetry, you can use the Gaggenau BO 450 612 which will fit into a 60cm cabinet without adjustments.  Most of the appliances in Chief are geared to American dimensions which are larger than European sizing, but there are a few tricks, like sometimes being able to find an appliance in a manufacturer's catalog that also sell in Europe.  
Good luck and feel free to ask more questions!
 

This happened to me yesterday and the solution was to send everything to layout as "Plot Lines" instead of "Live View".  Try resending each one as a "Plot Line".

Thank you!