@alien4u Thing I'm wary of is that the custom record could be updated by a UE but also directly or through uploads etc. Sounds like I may need to create a SuiteLet for the case where the record is updated from a UE trigger and a UE on the custom record for other circumstances

Your suitelet could be as simple as

record.load(params).save();

to trigger any UEs on the custom record.

When you say uploads are you referring to CSV imports? There is an option in CSV imports that allows you to trigger User Event scripts in the record.

@mattdahse User even triggered on create / edit of estimate As part of this it creates / updates a custom record. Further to this, new requirements expect that on create or change of certain fields on the custom record various further code needs to run. The problem, as I see it, is I need to be able to ascertain the old rec / new rec to establish changes have happened to the custom record if it's updated. Potentially a user could open the custom record and edit / save it or even directly create a record. Further to this, if the custom record has a flag on it and on create / edit this is set and a scheduled script runs to update certain fields too and some of those fields are fields I'm interested in if they have changed. It's a bit of a minefield and I'm battling in my head the cleanest approach without stepping on the toes of the various scripts running.

If you dont want the user to be able to edit or create a custom record, you could lock the record with a workflow