Assume: in a google sheet the attendance to courses is logged with crosses.
Goal is to get the last attendance date of a person and add 6 months to it. ( course needs to be followed every six months ).
I've tried to retrieve the date of the last course in one column and add the +6months immediately and tried to have the +6 months in the second column, but I didn't succeed in both attempts.
See this link for example google sheet: https://docs.google.com/spreadsheets/d/10DG2I4VgTlOHJ5TG0qH4pJ5hJ9zsYuJCgRzEtuiTE60/edit?usp=sharing