How does one combine possession and appositive comma usage in one sentence?
Why would you use the possessive for friend? In the first case, the subject is Tom which is modified by friend. You would therefore write
My friend Tom's object.
My friend's, Tom's object.
makes no sense, especially with that extra comma, but if you were to try and parse it, the meaning would be:
My friend has a "Tom's object" and I am referring to it.
You would need that comma if you were to write, for example:
My friend, Tom, has a green car.