Define a custom value list with the values "first visit" ; "second visit" ; "third visit"
Define a calculation field, cVisitList as:
List ( If ( Not IsEmpty ( Date of 1st visit ) ; "first visit" ) ; if ( Not IsEmpty ( Date of 2nd visit ) ; "second visit" ) ; if ( Not IsEmpty ( Date of 3rd visit ) ; "third visit" ) )
Put cVisitList on your layout and format it as a check box group with this custom value list. The quoted text in the calculation must exactly match a value in the custom value list for this to work.
Note: the above method works without redesigning your table, but if you added a related table to record the date of each visit, you gain flexibility and your needed check box field becomes easier to set up as well.
How do I get these checkboxes linked to each community? I do get the three checkboxes (first, second and third visit); but what I have in mind is kind of the display of a list of communities (rows) with three columns (column 1 = first visit; column 2 = second visit; column 3 = third visit) next to that list. I only want the names of the columns displayed, and thus after every comunity only three checkboxes.