I think the first option is the way to go. C# does not allow multiple inheritance anyway.

You can extract as many shared properties as possible, put them in an abstract class - inherited from ProductContent or VariationContent, then inherit from that class.

One other option is to define a IContact interface. You will still need to implement the properties in your catalog content types, but your business code can now only care about the interface, and forget about the actual type.

Regards.

/Q

Q,

To clarify, my second diagram doesn't show mutliple inheritance - it shows my products composed of a Contact, something like:

public class Contact()
{
    public string Firstname { get; }
    public string Surname { get; }
}

public class ProductTypeA: VariationContent
{
    public string Description { get; }
    public Contact Who { get; }
}

I guess you'd need a custom meta type or something for Commerce to be able to undertsand how to render the Contact type?

Regards

For easier mapping between metafields and properties, I would recommend to use primitive types, instead of composed types. Otherwise you might have to override a lot of code (which I'm not sure possible, we don't recommend it anyway)

/Q