Is there a way to safely modify instance class of RDS cluster instance from terraform?

Hi there,

I am currently using a RDS cluster with 2 instances: reader and writer. When trying to change the instance class through a terraform apply it just starts to modify both the instances at the same time: causing a short outage.

What I am looking for is a way to configure terraform configuration in such a way that when there is some instance modification terraform should first modify the reader, failover then modify the writer.

Can someone help me with this?