conditional fields in the perch interface

Hi,

When editing content in perch, Is there a way that based on a selection within a region say a drop down list of options. The selection loads the relevant fields for the user to complete. Each option in the drop down loads a different set of fields to fill in.

The only way I can think is having a choice of blocks with these varying fields pre defined in the template. But for my scenario it potentially means a lot of blocks templates.

Is this possible? or another way I'm missing?

For example conditionals are only available for the output of a template, not the actual template itself.

Thanks