In Pathfinder 1E, how do Greater Magic Fang and Amulet of Mighty Fists stack


My animal companion has an Amulet of Mighty Fists that only gives me, say, +1, Frost, without any enhancement bonus. So it’s a +2 equivalency, with a +1 enhancement bonus.

Let’s say that I then cast a Greater Magic Fang which would grant a +3.

I can see any of the following things happen.

  1. Nothing — there’s already an enhancement situation.
  2. No more Frost. It’s now a +3 enhancement bonus with no special abilities.
  3. +3/Frost — it takes the greater of the two enhancement bonuses and keeps the special abilities.

Honestly I can accept see any of these. Right now we’re playing that it’s the recipient’s choice of 1 or 2. Any opinions?