Updating Parent Table after Child Table has a record deleted

[Luis_DfG]

Hello, I have the following tables:

table A (Parent Table): Department
table B (Child Table): Users

table A has a column: # of Users which is a formula: Sum of all the User records that belong to that specific Department.

My question is: How can I tell Appsheet to recalculate the formula for # of Users when a register from the Child Table gets deleted?

I’ve tried to build this using Google Apps Script but sadly I cannot catch the record’s info from the Child Table when the action is a delete action.

Thanks