It seems that I was right why W wanted to take a photo of me.
"The process server (of divorce papers) will need a recent photo and description of your spouse."
I mean, I think she could just take a picture of you without needing the kids or a pose to function for a process server.
I think you are spending all of your energy trying to analyze her reactions in so much detail. I think it's a waste. I recommend to have patience and in time, her intentions will reveal themselves.
Maybe instead, continue to focus on what is important. Securing your time with the kids. GAL. and so on.
It seems like there are a LOT of school events, and each time, there is a lot of interaction between you and W. How can you start to be darker/more mysterious towards her?