>OK well the progress on this is that I found out that I had to save the form as a DLL, so I did that but the source project was still part of my overall solution. This came up with all sorts of wonderful errors that are totally incomprehensible to me.
>
>I moved the ParentClass project out to a separate solution, rebuilt it and magically now I can add one of these forms to my proper project.
>
>Except...I cannot get the RegisterPrimaryBizObj method to be recognised - can you tell me which namespace it is located in please?

If you have created a subclass of mmMaintenanceForm then you should be able to enter the following in your form's source code:

this.RegisterPrimaryBizObj

And you should see the method RegisterPrimaryBizObj. If you are NOT seeing this method, then you are definitely not subclassed from mmMaintenanceForm.

Regards.,