How do you set multiple check boxes so that at least two of them must be selected?

A client has a section on their PDF which has three check boxes, and they need it set so that only one or two of the three options can be selected before finalising the document. The problem they're facing is that when people fill out the form, they tick all three when they're only supposed to select one or two. I know there's a way to link check boxes so that at least one of them is required, but setting two of them has me stumped. I'm guessing something would need to happen where the third remaining check box can't be checked, or some type of warning would appear. Is anything like this even possible?

Any help would be appreciated.