I hope Autodesk can have a easier way to edit the "input/output parameter" sequence. Today I found I cannot even delete a parameter. Whenever I want to delete a parameter, SAC just frozen.
You can change the parameter order manually by editing the .atc file contained in the subassembly pkt file. Use Notepad or another text editor to reorder the <Params> group in this file. (I would make a backup copy of the pkt file first.)
The pkt file is just a zip file containing all of the data files used to define the subassembly.
Great tip.
I had to edit the XAML file also to get the parameter reordering to work.
See attached screenshot, then simply rename .pkt to .zip
then edit atc file and again drag into zip file.
later again .zip to .pkt and import to civil 3d.