Using formulas in automation actions

[BB-Bacuti]

I have a table that has a parent child relationship setup through ID and parent_ID fields. I have number fields on each record and when an automation is triggered I want to add the child record's field 2 and field 3 values to the parent record's field 1 value. I've setup the automation to trigger from the child record. It looks up the parent record, but when I try to update the parent record and set it's field1 value to current field1 value+child field 2+child field 3, I get an error.

How can use a simple formula like "+" in the automation action?

[Sho]

Automation does not allow formulas, so you will need a formula field for the automation output and write that field to a field in the target table.
If this is not possible, scripting or other steps may be required.

Also, if there is already a linked table, there should be no need to find records by simply referencing the record ID's in the linked table.

[BB-Bacuti]

Ok. Thanks for the response. Formula field will not work for me because it's a recursive logic in the automation and I do not know upfront, how many such records I will need to add. i.e., scripting may be the only option