<aside> ✅ In the example below, everytime a checkbox is ticked, the original date is pushed 3 days. This will only occur at a maximum 3 times with a 9 day gap. Of course, you can add more checkboxes and alter the space between each repetition via a simple formula.
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if(prop("Session 3"), dateAdd(prop("Date"), 9, "days"), if(prop("Session 2"), dateAdd(prop("Date"), 6, "days"), if(prop("Session 1"), dateAdd(prop("Date"), 3, "days"), prop("Date"))))
Alt → Date Pushing With Select
dateAdd(prop("Date"), toNumber(prop("Session 1")) + toNumber(prop("Session 2")) + toNumber(prop("Session 3")), "days")