Who's ice cream is it really?

[EvansAndThePrince]

DH and I are having a disagreement about ice cream.

Person A bought a 2 pack of gu desserts. They ate theirs and then person B offered to swap their dessert for a tub of ice cream that was already in the freezer and "belonged" to person A.

Person B then ate the gu dessert, having forgotten about the deal. They replaced the dessert the next day but as they only come in a two pack, they are the second dessert.

Who's is the ice cream now?
Person B thinks that their second dessert is irrelevant to the situation.

Needless to say, this is lighthearted!!

Get all remaining ice cream and Gu out, split between 2 bowls and create an ice cream sundae. If there are no pregnant people Baileys can be poured over.

For complete transparency and fairness the person that didn't dish up gets to choose theirs first.

Please do draw up a dessert sharing procedure to avoid future issues.

Before:
Desert 1 - Person A
Desert 2 - Person B
Ice-cream tub - Person A
Desert 3 - Person A
Desert 4 - Person B

Plan/Swap
Desert 1 - Person A
Desert 2 - Person A
Ice-cream tub - Person B
Desert 3 - Person A
Desert 4 - Person B
~~ A gets 3 deserts, B gets 1 desert + 1 ice-cream tub

Solution
Desert 1 - Person A
Desert 2 - Person B
Ice-cream tub - Person B
Desert 3 - Person A
Desert 4 - Person A

The only solution for A to get all 3 of their deserts as owed to them in the swap is to give them both of the new deserts.

I just saw your follow-up (silly me didn't read far enough).

The swap was A's ice-cream for B's desert. B ate their desert therefore it's A's ice-cream again.

Otherwise, it's as I said above to go back to the "original" swap.