Hi @Marty_Nator and @Federico_Stefanato
Sorry to bump here but while reading i’ve had a simple idea that maybe can simplify the work
Warning: extremely basic concept, the advanced answer have been already provided by Federico so this is just an addition to that!
If for every “payment” row you could use a button instead of using the checkboxes you could use that to check whatever box you need AND copy that row with “date + 1month” in the same table/in another
Also, if a batch selector is needed you can always use a checkbox for every row and a button below the table that press every button of that table that have the checkbox=true
Hope that’s clear, in case i can prepare a fast dummy doc to show the concept