First, you start a synchronization schema change. This is required for most schema changes that affect synchronizing tables. This statement changes the script version that is used to synchronize the subscription, and locks the affected table so the schema change can proceed safely.

Execute the following SQL on the remote database using the instance of Interactive SQL that's connected to the remote database:

START SYNCHRONIZATION SCHEMA CHANGE
FOR TABLES customer
SET SCRIPT VERSION = 'my_ver2';

Next, add the new column to the customer table with the following SQL:

ALTER TABLE customer ADD cell_phone varchar(12) default null;

Lasting, close the schema change which unlocks the tables.

STOP SYNCHRONIZATION SCHEMA CHANGE;