Example time.

Best friends reads-

Commit 1 Foundation: Your stun attack get's +1 to it's rating.

I play hammer of the Gods (Stun 2)

I enhance with Paul's Gi(Giving my attack Stun 2)

Now, I enhance with Best Friends.

Do both of my stun ratings get +1? Do I now have two Stun 3's? Or one stun 2 and one stun 3? or one Stun 5?

I'm assuming based on the multiple ruling, when you add multiple to a Card(Using for example Tira's Ability) it doesn't add to the rating, it add's another instance of multiple, I would assume Paul's Gi(and Manaical Laughter) function the Same. So when Adding to the Rating with Best friends(Or Tandoya's enhance) does it add rating to both instances of stun, or just a single instance?

Thank you.

this came up at our sealed event the other day and Tag ruled that it only adds to one, but i am anxious to see how others see it

See. i'm not sure I agree. If it were going to only add +1 to a single rating, wouldn't it read "Your Stun ability get's +1 to it's rating" that would refer to a single instance of stun. The Card says "Your stun attack" making me feel like that all the stun ratings on said attack would be increased by 1.

Well, since it says "its stun rating" in singular, I believe you pick one of them and increase it by 1. That's how I've always seen it.

Hammer of the Gods has Stun:2. Then you give it a second Stun:2 with Paul's Gi, so when you go to use Best Friends, since it specifies it's its stun rating (not ratingS), you choose one of them. End result is you have a Stun:2 and a Stun:3 on the card. Which one is the 3 is up to you when you play Best Friends.

It's the same as reducing the Multiple rating of your attack with Solitary Assassin. It only changes one of the abilities (your choice).