If the child waypoints all have some common item, it should be possible to filter for those caches from the "Children" tab under filters. However, if you only want to send specific child waypoints from a cache that has multiple child waypoints, i.e. only parking coordinates from a cache that has trail head and other waypoints set as well, that's above my level. If you go to one of the numerous GSAK help forums, perhaps someone might write a RegEx statement for you that would pull out only what you want. There are people on some of the forums with knowledge many orders of magnitude above mine when it comes to that sort of thing.