Edit settings in designer of embedded SimpleView in containi

Been spinning my gears around this for a while and can't seem to find clear documentation on how to do what would seem to be somewhat simple task.

I have an existing "SimpleView" widget/Control already registered in the CMS with a custom simple designer and everything... This is used on many places throughout the site. I'm trying to develop another "SimpleView" widget/Control that embeds the aforementioned SimpleView. I can get the thing to show up by putting a tag reference to it in the new widget's .ascx  file... but I can't quite figure out how to make this inner embedded widget's properties editable in the CMS using the designer as I can do when it is standing alone (short of just duplicating the business logic behind it the new codebehind) - hope I'm just missing something simple here.