If you are going to give food to people on vacation, you should give it to anyone who comes by, regardless if they are day hiking or thru hiking. I have seen a few of these things get ugly when some are denied and the "special class" gets to partake. I would think however, your group would want to do something for those who cannot be on vacation and have a difficult time getting food on their tables, but that's just me.
Proselytizing on the trail using food as bait to get a better "bang for your buck" may be subject to prohibition and commercial food service regulations. It may be wise to consult the NPS and local county offices to be sure you are legal.