Question

I've created 2 tables, one for main task and one for sub tasks. These 2 tables are related.

One main task can have > 1 subtasks.

I also have an overview table with relation and rollups to give me an overview of how many main tasks I have and how many subtasks I have in total.

When I delete my main task, my subtask that corresponds to the main tasks does not get deleted. This screws up my total no. of tasks counts.

Answer 1

You should not delete them, you should mark them as done with a checkbox and have a formula that when all subtasks are done, the main one marks as done as well.

Your total will not fail this way.