Creating a 'If-need-be' poll is a great way to give your participants another option rather than just saying yes they can attend, or no they can't. To enable this feature, tick the box "if need be" during step 3 of the poll creation.
When your participants make their selections in your poll they can choose 'if-need-be' by clicking the option twice. When 'if-need-be' is enabled the box will turn orange.
Try it now: Create a yes-no-ifneedbe poll