If she doesnt im going to go with her, ask her to introduce me to the host, the say she you later and not talk to her again until we leave.
Have fun at the BBQ! Consider taking another step back from controlling the experience--at the beginning, let her introduce you to whomever she wants to, politely excuse yourself to use the restroom or get some food, then focus on others. See her again whenever you see her again whether that turns out to be "sooner" or "later".
