Help the eccentric billionaire's lawyer finish drafting this unusual will.

"In the highly unlikely event of my disappearance, if my pet llama, Reginald, ____ to inherit my vast fortune, the global stock market would surely collapse."

The correct answer is were.

When talking about a highly unlikely or purely hypothetical future event, we can use the structure If + subject + were + to + infinitive (If my llama were to inherit).

Because this is a hypothetical scenario (the subjunctive mood), "were" is the strictly correct choice for all subjects, even singular ones like "llama". "Is" would be used for a real possibility, while "would" and "did" are grammatically invalid before "to inherit" in an if-clause.