Cann I Add New Column In Subscription Database Table

Hi

I am learning Sql server 2005 replication.

My requirement is.

1.) Subscribe a Master database
2.) I have to add a timestamp column in every table of subscriber database ( Note: the column will not be in publication database)

I have two sql server

server 1 : I made Merger publication

server 2 : I made subscription of the same

But when i tried to create a column in the Subscriber database table its giving the following error

Validation warnings

warnings were encountered during the pre-save validation process, and might
result in a failute during save. Do you want to continue attempt to save?

''Table1' table
- Error validating the default for column 'rowguid'.

I clicked "Yes"


Post -Save Notication
Errors were encountered during the save process. Some database objects were not saved.

'Table1' table
- Unable to modify table.
The DDL statement cannot be performed at the Subscriber or Republisher.
The DDL operation failed inside merge DDL replication manipulation.
The transaction ended in the trigger. The batch has been aborted.


clicked ok

User canceled out of save diaglog

Can i add a new column to subscriber database table if so please guide me?