Unwanted advice

I had the first bit of unwanted advice. We had an unexpected death in the family. So many people are meeting Owen for the first time. My great aunt that while I do love her, she drives me crazy. Came in and said oh my goodness! You need to get that baby off his back ! His head is so flat! First of all... hi nice to see you too. Second. That babys name is owen. Third. Owen is only on his back at night and in his car seat. During the day I'm holding him in a sitting position or he lays on his tummy on his mat. She just kept saying he needs to be on his side or tummy. Not listening to me saying hes on his tummy half of the day. I got so mad I couldn't stand it . Even my mom was trying to tell her he doesn't lay on his back that often.