I use Acrobat and or LiveCycle to do forms in, though. I can look later if I can use ID. Should be able to, though.
But I gotta say. I probably would likely tell the client he needs to use the radio buttons due to their nature.
Is there a way to make a checkbox function like a radio button?
Actually you want a radio button, but have it appear as a checkbox. You can do this in Acrobat by changing the property of the button, selecting a [check] for the button style. You can kinda of accomplish this in Indesign, by creating a radio button, and change the [click on] appearance to a check mark graphic or glyph. The problem with this method is that regardless of the various appearance states, the button by default remains as a true radio. When viewed in Acrobat/Reader, you can select the button and have a check mark appear and it functions as a radio button, but the initial appearance is an unchecked circle button style.