What do we do with "...my son Scott...?" Comma or not?
This is the "essential/nonessential" dilemma, the hardest concept in all of punctuation. I would suggest that you read the entire chapter in my book on this. It is Chapter 4. The rule is very difficult to condense into a few sentences. When I explain it, it is about 30 slides in a presentation.
Here is a brief summary of the rule: It goes to whether the appositive is needed to DEFINE the word it is renaming. Would communication be lost if the appositive were removed?
...my friend Bill...
...my husband, Bill...
In the first one, the assumption is that I have many friends. I am using the name "Bill" to define which friend I am talking about. It is "essential." A pair of commas would mean I could take it out. So we do not want commas.
In the second one, I have just one husband. Giving his name is "extra." He is already defined in the word "husband." His name is "nonessential" to DEFINE him. The commas say the name could be taken out.
When it is "...my son Scott...," the problem is that you may not know how many sons. When you don't know, use no commas.
A further problem with this concept is that people use "essential/nonessential" incorrectly. It applies ONLY to appositives, participles, and adjective clauses. There is no such thing as an adverb that is "nonessential" to the meaning of the sentence.
There is much more to this explanation, but this is enough for now.
Happy punctuating!
Margie