The recent adventure Tomb of Annihilation released by WotC includes allies that can join the party. As an open-world adventure spanning multiple PC levels and Tiers, PCs could potentially gain allies more powerful than themselves such as the NPCs below.
Spoilers:
Artus Cimber with his Ring of Winter (CR 7)
Dragonbait (CR 5)
How does one calculate awarded experience when the PCs have allies that are more powerful than themselves in Adventurers League?
We are wondering if there is an official formula - something like:
$$\text{Awarded_XP} = \text{Received_XP} \times \frac{\text{Expected CR}}{\text{Actual CR}}$$
As opposed to the answers to the question Determining "level" of an NPC ally for purpose of budgeting encounter XP, we are looking for official Adventurers League guidance or acceptable practices — not homebrew suggestions.