How to Rename Table or Field With Merge Replication
You could do it this way:


Add the new field.
Force a software upgrade that includes the logic to insert new data into the new field and to read the data from the new field if it is not null, otherwise to read that field from the old field. ( in case of update: you read the value from the old field then do an update to the new field )
Wait for a while, perhaps a month till you are sure that all clients have upgraded your software.
Migrate data from the old field to the new field if the new field is null.
Delete the old field.