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".
This is plan A.
There is an art to breaking away. Do not do it too soon. Do not wait too long. You definitely want to do it before she does. A good time is when it is just you her and one other person. As long as you are actively in the covo, stay. Once the convo goes to just the two of them talking back and forth without you, excuse yourself to the restroom.
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712
