ACF Nested Repeater fields
ACF allows nested repeater fields, as described here: https://www.advancedcustomfields.com/resources/working-with-nested-repeaters/ This is where you have a repeater field, and then inside that field you have a second repeater. Currently your software only sees the parent repeater and not the internal children ones. These are also described on the page: https://www.advancedcustomfields.com/resources/repeater/ as Nested Loops.