Extend the notification definition to be based on non financial activities (change audit) and financial activities (transaction log).
A custom field value is change and based on the change event and the new value, a notification must fly out as a SMS, EMAIL or to a 3rd party system through a webhook.
Currently any non-financial change it is captured under the *Activity* event which is too general and cannot offer an isolation about which field got the change and how.
Mambu already keeps a track of the activities for audit purposes, hereby this can be used as event sourcing for the notifications.
The balance of an account can be changed by financial transactions which are not captured by the current events: interest applied, tax applied, fee applied or repayment schedule gets changed.
The transaction log is the source of truth for the balance, hereby this can be used as the event source for the notifications.