Who are or who is? [duplicate]

It would be who is planning...?

You can find the explanation here _{(TheGrammarExchange)}

"When 'who' and 'what' are used to ask for the subject of a clause, they most often have singular verbs, even if the question expects a plural answer:

Who is working tomorrow? Phil, Lucy and Shareena (are working tomorrow)...

When "who" and 'what' are used to ask for the complement of a clause, they can have plural verbs.

Who are your closest friends?

So the grammatical rule would be that when "who" is not followed by a noun that refers to it, the verb is singular. However, when there is a plural noun that serves as the predicate nominative for "who," the verb is plural.

Who speaks Spanish in this class? All thirty of us, teacher.

Who is voting for incumbent? The whole town, all 50,000 of us.

Who wants to win the lottery? Everybody!

but

Who are those students? Who are the people who are voting for the incumbent? Who are the people who want to win the lottery?