Our Personalized Touring Plan software supports "big" character greetings that have posted wait times, are continuous scheduled, and have well-managed queues (for example, Meet Mickey at Town Square Theater at Magic Kingdom). However, we do not have the necessary data about schedules and wait times to make reliable predictions about the numerous "minor" character greetings around the theme parks. If you do not see a character greeting that you want in the last of attractions you can add, it's not available in our software.
On workaround is to add a break to represent the chunk of time that you'd like to spend meeting characters. For example, you might decided to spend two hours starting at 11 AM, and you could create a 120-minute break starting at 11:00 AM to represent that. Greeting characters is not generally a time-efficient thing to do, so be sure to be patient and to give yourself plenty of time.