I've been flying for 25 years and all of the clubs I have belonged to have the same rule: A pilot that declares himself for landing has the right of way. The father/son should not have been on the field while a plane is in the air. They should have stayed at a designated pilot station to do their taxi practice. Once Mark declared his intentions they should have vacated the runway to a safe distance. I fly in Ohio and our winds change direction on us all the time, just because you takeoff on the east/west runway doesn't mean you are committed to land on that runway if the wind changes. That could create an unsafe condition if you force a person to land crosswind, especially a newbie like Mark. I think you should have nicely said something to them, they simply may not know the field etiquette (s) yet.