Everyone asks this. I have a sister and we have different dads, so in all fairness to my sister I call my dad Michael just like she does and everyone else in my family. It works out fairly this way in my family. I do call my dad “Dad” sometimes. If others look at this as a disrespectful thing then you can talk to my mom about it. I never started it, I was taught to do it this way.
So, yes, Michael is definitely Farrah’s biological father, but the reasoning is a little different than what was stated on my original post (linked above). I still think it’s odd that she calls him by his first name, but I do know of others who do the same. The fairness thing is weird though. I’m not about to have my daughter call her stepmother “mom” just because her half-sister does. But to each his own.