Multiple answer questions with mandatory selections?

Good morning.

I've been tasked with making an interesting question wherein there are 13 possible answers, with 3 mandatory answers that must be selected.

So the idea is, as long as you get those three selected, it doesn't matter how many others are ticked/unticked. They're all technically correct answers, but for the purpose of the question, those 3 must be correct.

I've been trying a few ways to do it, without success. I thought I could have the question widget increment a number when the correct choices are ticked and submitted, then check that number is >=3 on the following page - but Lectora doesn't allow me to have individual feedback in a multiple choice question with more than one response.

Are there any other bright ideas how to accomplish this? I'm assuming there's a more simple way than I am looking at...

Thanks in advance.