BCS Budget control - how to check a different value

Hi,

I will understand if there is a possibility, without changing the standard functionality of FM budget checks, and eventually using some user exit, to modify the value that an FI document check on Budget availability in the moment that the document is posted.

Meaning, I need a functionality more or less like "tolerance profile" that works with % and value limit, but with a dynamic value of tolerance, that will be calculated via a user exit anytime an FI document is posted.

For example I need to check if there is 85€ available for a Good receipt of 100€, or check if there is 76€ of available for an invoice of 140€.

Thanks

BR

Giovanni