Delete Before Paste Method

Below is a detailed method for moving a section of circuitry from one schematic sheet to another. It is not complicated nor is it time consuming but... it does require the user to momentarily disable the synchronization between the schematic and its associated layout (brd) file and... one must delete the original circuit section after it is CUT but before it is PASTED; if you lose the context for any reason the circuit may be lost. Saving your files can offer protection (so do not skip that step).

Example: Moving a Circuit to a Different Sheet

SAVE your Files!
"Save All" on the File menu (File -> Save All) or click the save icon on BOTH the schematic window AND the layout window. This step is to protect your data in case of a mistake.
Close the layout file.
Make VERY sure the layout window is actually CLOSED and not just minimized! I do this by clicking the window X button (usually on top right of the window title bar). If you fail to close the layout window then when you delete the circuit from the schematic it will remove the layout also and you will lose the layout traces
Select the Objects to Move
If you have a group of objects to move (usually the case for me) then use the GROUP command and the mouse to select the objects to be moved. If it is a single object go to the next step. Of course you can select a single object using the GROUP function if you want.
Mark the circuit
Use the CUT command to mark the object (or group of objects). If it is a group then click the CUT command then move the mouse into the group and right click to select the group. If it is a single object such as a symbol or gate then click the CUT button and left click the object.
Delete the Circuit
Careful here. Select the Delete function and then (if you selected a group) right click near the group. If you selected a single object then left click the object.
Go to the new sheet
Click the Sheet selector and select the destination sheet. If the sheet does not yet exist you can select "new" from the list and create it directly
Paste the Circuit
In the new sheet select the PASTE command and you should see a copy of the circuit under you curser. Place it as you like and left click.
Re-open the layout file.
Click the BOARD icon to re-open the layout file. If all has gone well it will open with no complaint and your layout will still be intact. It is importent to remember to reopen your layout file not only to check for errors but so that your subsequent changes will be reflected in your layout file.
If things go poorly...
The quickest way to recover is to simply quit both the schematic and layout without saving. Because you saved your files when you started (you did save them right?) they will still be intact now since the changes are only recorded when you save the files.