Use the Dynamic Branches options on the Pattern Options 
Holes tab to automatically position and cut branch holes into rectangular straight developments.
This feature allows holes to be intelligently cut into rectangular straight developments when positioning taps\shoes, or any object, to the face of straight duct (CID 1866). This eliminates the need to manually edit developments in CAMduct.
The following options on the Pattern Options Holes tab are associated with this feature:
Active: When this option is selected, dynamic holes will be positioned and cut according to how the options below are configured. This option is the on/off switch for the dynamic hole feature. With this option enabled, the association is kept between the straight and branch parts.
Draw Holes: When this option is selected, holes are drawn\displayed when the model is displayed in 3D viewers\Fab Viewer. The hole is displayed using the "inside color" specified in the viewer setting. Disable (remove the check mark on) this option if you do not want holes to be drawn in 3D viewers\Fab Viewer.
Develop Holes: When this option is selected, dynamic holes are cut on the part. Disable (remove the check mark on) this option if you do not want holes to be developed (cut). The Dynamic Hole will be displayed using the “Cutting – Inner color” from the main database.
Dynamic Hole Adjust: This option lets you adjust the size of the hole that is cut (+ve or -ve) since the hole may not be that same size as the branch.
Attached Items: (ESTmep only) When Ignore is selected, attached items are ignored. When Auto Repair is selected, the hole position is maintained, even if the branch size or position changes, automatically updating the dynamic holes without the need to use the UPDATEDYNAMICHOLES command. This option is available in ESTmep. CADmep holes still require manual updates.
Pattern-specific Overrides
The following pattern-specific overrides are available when using dynamic holes:
Fix Relative: Any pattern has the ability to add a hole to the development of the straight. To do this, set it to Fix Relative.
Dynamic Hole Adjust: Some CIDs have overrides for the size of the hole cut in the development; for example, CIDs 7, 24, 504.
Machine Cut: CID 866 contains an option to set it to Machine Cut if a hole is dynamically added.
Updating Dynamic Branch Holes
Type the following command at the command line to either remove a hole after a pattern has been moved in the model, or to add a hole if a pattern has been moved onto the side of a straight: UDH (UPDATEDYNAMICHOLES). This command refreshes the model and developments, if you have moved, edited or deleted the associated branch.
If the association between the branch and straight changes, the user will be required to use the UPDATEDYNAMICHOLES command to refresh the hole position on the straight.
To update the dynamic hole, including the developments from the straight, you can use the UPDATEDYNAMICHOLES command, and only select the associated branches you required. Any holes belonging to associated branches not included in the selection will be removed.
Dynamic Branch Holes in Design Lines
Dynamic Holes automatically work with Design Lines, so wherever there is a branch, a Dynamic Hole will be associated with the straight duct without the need to fix relative in the CAD Takeoff dialog.
If you move the branch, the Dynamic Hole will also update and move, without the need to use the UPDATEDYNAMICHOLES command to refresh the associated branch hole.