What are the uses of 'having?'

When I possess something I can say

I have a pen.

But can I say:

1. I am having a pen

As far as I know "be + having" is used when I consume or enjoy something like I am having breakfast.

What is the rule when a third person possesses something?

Murad has a car.

This sentence is correct.

But are these sentences correct:

2. Murad is having a car.
3. Murad is having his dinner.
4. Murad was having his dinner.