Hi OPhiA sister,
Some NPC groups and even some OPA chapters do their jerseys and shirts differently than they do than you chapter. They decide to vary on the shirts to try something different. For example, I have OPA shirts in white, different shades of blue, yellow, red and garnet (to reflect one of our school's colors). I don't have a OPA jersery, but if I wanted to do it in colors besides the blues and yellow, that's my choice. One of my friends had a shirt made for another sister with part of the Texas flag (she's from there). My OPA bag has Mickey Mouse on it. With DST and other NPHC groups, I'll have to co-sign with sigmadiva--that is a big no-no. My DST shirts come in three colors--red, white and black(and I have a lot of them).
I also understand where you're coming from with the familes. I was an Alpha Angel with OPA in college. You become in the family when you get your big sis and your little sis becomes a member as well. It is to bring unity and to build a closer relationship with some of your sisters.
I hope my explanation helps!