Objeto Indirecto

Question

I was given the sentence

¿Quiénes os están haciendo las camas?

and asked to put it into the form:

Ellos……….…están haciendo

using the objeto indirecto (OI) and the objeto directo (OD).

The OD is quite obviously "las camas", so the pronoun would be "las".
But I can't for the life of me work out what the OI is, is it "os" or is it "ellos", i.e is the pronoun "os" or "se"?

Finally, what the resulting sentence be:

Ellos os las están haciendo

or

Ellos se las están haciendo

This has been bugging me for a while so I'd appreciate any answers!

Answer 1

Let's start by explaining what the indirect object is not.

The indirect object can't be se/ellos, because whatever the IO is, it has to match the pronoun "os" used in the original question.

That said, I interpret this question as "who is making your beds?" We know the indirect object is "you", which is inferred from the possessive pronoun"your", just as you said. So now the question is which version of "your" do we use?

Since the new sentence's indirect object has to match the pronoun in the original sentence, our only choice is "os."

The correct answer therefore is (1) "Ellos os las están haciendo."

Answer 2

"¿Quiénes os están haciendo las camas?"

Ellos las están haciendo.

Ellos nos las están haciendo.