Google sheets; check boxes with an "if statement"

I'm working on a record keeping system for the animal room in our small museum using google sheets. Some of our animals eat every other day.

I have a function that puts the date at the top of the daily sheet. I need a function which will look at the date and show a checkable box if it's an even date or a line if it's an odd date (or vice versa). But I can't get the check box into the "or" function.

Super grateful for any help!