Submit RPC call.
Change session keys.
Set session key.
Pre-sealed block for proposal atappears in Validator B and disappears in Validator A logs. You can do it by running the following command in the Validator Nodes root directory:
docker-compose logs -f --tail=1000 | grep "Pre-sealed block for proposal at"
docker-compose stop add_validator_node_customin order to update either the Validator A itself or Machine A.