Launch the Part Alternative From from another form

Just wondering if anyone had any suggestions to loading up the part alternative form (which appears when you click on the substitute or Comparative part buttons on the sales order line)

I’d like to add similar functionality to the PO Line.

I took a look at process calling and nothing pops up when you click on the button in customisation mode.

The Alternate Part Form appears to be a subform (AlternatePartForm) in the SalesOrder assembly. I know in the past with Handheld it was a simple as setting up a process calling and a menu item, configure a customisation. Then update the Arguments column in the table to include the switch -formName and put in the subform name after that. In this instance it’s not working. I am wondering if there is some difference between the Handheld forms vs a normal form.

Any input appreciated.