This is a very frequent topic and Feature Request, which comes in many forms. These Tracker Items have the equivalent of 14 to 15 votes. Indeed David Plumley was trying to accomplish this by the use of APRS position, while others have been trying to send via IP setup, and many other ideas to accomplish the goal.
FS#1595 - sync WP Plot a waypoint received via a NMEA WPT sentence
FS#2166 - APRS position is not displayed upon receipt of a WPL sentence, t
FS#2205 - sync Send Waypoints & Routes to Net type Dataports from Route &
FS#2160 - Synchronize Settings,Waypoints, Routes, Odraw, Navobj over IP a
FS#2226 - sync OPEN CPN as a slave or a master in front of the GPS for nav
From the wiki and a lenthy and productive CF thread
Sending waypoints & routes over IP
Judging from the number of efforts, suggestions and related feature requests, it appears this might be considered a reasonably high priority by a segment of the users.