I had emailed Kevin about subclassing the Mere Mortals objects, which relates to this topic, but thought I'd reply in the thread instead of directly to Kevin so that everyone can benefit from his expertise.

I am building at least three levels of classes at my company.
* Level1 has the Mere Mortals classes. I do not want to modify any of these directly because it is likely they will change in upcoming versions and I don't want to redo my work.
* Level2 are my company level classes. These will have functionality built on top of the Mere Mortals classes that is common to my entire company.
* Level3 are my application specific classes.

Since I have already seen the need to subclass some of the business classes as well as the UI classes, I thought I would just create projects for my company level and application level classes and subclass all of the Mere Mortals classes in one shot. Kevin advised against that and suggested I use the Factory classes instead. I still don't understand why I should not subclass everything. Any input would be welcome!

Kevin's response: "Unfortunately, we don’t have a subclassing utility although we plan on creating one. I recommend subclassing only the UI controls rather than subclassing everything. We’ve made it easy by means of our factory class to allow you to subclass and extend MM .NET components on an “as needed” basis."