[TYPO3-mvc] domain modelling for extensibility

[Christian Kartnig]

Hi there!

I have a question on how to model my domain in extbase.

In my domain there are about 12 different request forms, each containing 
a lot of fields. Roughly 40 percent of the fields are the same in every 
request form (but not easy to semantically extract).
The business logic in the controller is nearly identical for each 
request form.

How should I design the model so that I can
- list (and filter) all request forms together, regardless of their type
- easily add new fields in any of the request forms
- easily add totally new request forms (copy & paste, reuse 
templates/partials?)

Should I use inheritance or relations or should I treat each requestform 
independently for best extensibility?

Thanks for your hints!

best Regards,
Christian