Impossible to copy the properties of one branch to another

[lishnih@…]

How can I do something like this?

db_conn:

mysql_1: &mysql_1

type: mysql

host: localhost

name: root

pass: 54321

db:

default:

*mysql_1 <- it must copy all fields from mysql_1

pass: 12345 <- and append this field

... and why can not I do this?

db:

default:

db_conn.mysql_1

pass: 12345