Hey, I just was reading your response to Bella's post and it made me tear up. My situation is almost exactly like yours, except that my dad passed away in 2008, and his cancer was of the esophagus. He didn't even know he had it until he went to the hospital as he'd gotten really sick, and within a week he was in hospice and mentally not there, and within a week he was gone.

And just like you, I'm the baby and he was there for my other 2 sisters' weddings (though he was gone for my sister's wedding in '09), and my FI never got to meet him even though he was right by my side during those two weeks in the hospital.
I have a really great stepdad that's been in my life for over 20 years, but I've decided not to do any sort of stepfather/daughter dance because I just don't think I can handle it in the absence of my dad, and I'm having my big brother walk me down the aisle. It's still unsure as to whether FMIL is attending (it's a DW), but if she does, I'm really hoping that FI is OK with not doing the mother/son dance.