There are several rules and restrictions for altering column datatypes.
You cannot change the declared column datatype (the datatype in the primary table) if it is used in a where clause in a subscription or a where clause in an article.
You cannot change the rs_address datatype.
You can change the column datatype to text, unitext, image, rawobject, or rawobject in row only if it is not a primary key or searchable column.
To change the published (replicate) datatype, you must include the declared (primary) datatype of a column (whether it is being changed or not) and the [map to] clause.
Altering a column’s datatype and nullability affects the same column across all replication definitions for a table. However, changes between a rawobject or rawobject in row and its base datatype, affects only the current replication definition.
Use column nullability changes for text, unitext, image, and rawobject columns only.