In need of a command that when I click on the Microstation drawing it opens it in AutoCAD however when I'm done with modifications its still saved as Microstation. If anyone has any good idea's I'm all ears. Thank you.
Look into command DGNEXPORT and DGNIMPORT.
Reassociation of a file extension does not work here.
One has to open AutoCAD and either Import or Export from there.
If no toolbar (or ribbon) for these commands, create one is not that difficult.