Thanksgiving Argument

My parents own a linen delivery business, and sometimes restaurant need a special delivery when they run out of something (napkins, aprons, etc.). On Wednesday night, I made a trip out to the Westfield Charlestons to help out my dad because they needed napkins around 9 PM. I didn't mind doing this because he had been drinking and I hadn't, it's a family business so I have to help. Come Friday night I have plans with a girl. While I am sitting at my house with my family waiting for her to let me know she is ready to pick her up, my dad gets a call that Charleston's is yet AGAIN out of napkins and needs a special delivery. He tells me it is my job and I have to do it. I argue that I have had plans with this girl all week, and never get to see her since I am always at BSU.  He tells me it is a family business so that should come first, so I claim that my sister should do it, seeing how she isn't doing anything but sitting on her ass watching TV. My sister argues, but in turn my dad realizes I make a valid point, and she ends up doing it. The ethos is that I was very angry when my dad put the responsibility on me when i had plans, and my sister didn't. The pathos is that I already made a delivery that week and my sister didn't. The logos is that I had done my fair share of help. I had plans and my sister wasn't doing anything, so it made more sense for her to take care of the job.