Id missing weekdays in a table and add them copying from existing weekdays

[Eso_Surveyors]

hi, all, back to the community after a long while, but never away from appsheet.
excited about automation.
this is my challenge:
i import into a table this csv data:
State, Last Name, First Name, Shift Start Date, Shift Total Time.
5 states, 100 last/first names, most make entries for the week’s work but not all 7 days, for example Saturdays, Sundays.
i need to automate once weekly on report day, inserting the weekdays missing for each state+L/F name with zero in Shift Total Time.
can’t get my head around how check record by record for a missing weekday in the file for that state/LFname then create a single line replicating all but ShiftTotalTime zero.
thanks in advance for any ideas.