I guess there are two questions. In terms of an individual who would be communicating with a public office holder--which a parliamentary secretary is--they would need to determine whether an initial registration is filed.
What is not required, because the parliamentary secretary is not a designated public office holder, is the requirement to file a monthly communication report in terms of a monthly communication. The communication with the public office holder--if it is communicating--is still defined under the act as registerable activity.