My oldest child is from my wife's first marriage. I met my wife when the baby was 8 months old and I've never called her my "step" daughter. Here we are 41 years later...
If you want to that’s your choice, but most people are not going to value another person’s child as much as they value their own.
She has a father. Its not him. Anything she inherits from her father she should not be expected to share with her step and half siblings that are not that man’s children.
Bump
Bless you.