Save and load a model with extended classes from nn.Module

Hello community,

I have a question regarding models with extended classes.

How do I handle with models which are built by extended classes from nn.Module which have some specific features in itself?

Can I load it without any consideration? Or should I recreate the classes/some methods (if not, in which cases is a recreation of classes necessary; forward function and so on)?

And what should I consider If I load a model and want to extend it?

best regards!