This simplest way possible. If the rate change can be processed via an endpoint that endpoint then updates the 4 databases. If talking to ACID databases, do a 2

This simplest way possible. If the rate change can be processed via an endpoint that endpoint then updates the 4 databases. If talking to ACID databases, do a 2 phase commit to reduce the chance of them getting out of sync. Send me 10% of your consulting fee please :-)