Most Helpful Guy
This is what happens when people get so wrapped up in Facebook/social media and take it way too seriously. You start overanalyzing the smallest (and sometimes non-existent) things which causes you to get worked up.
His family used the pic for a family moment and it being his dad, was tagging people for the purpose of showing other family. When people start feeling left out simply because they weren't tagged in some post on Facebook, you might need to dial back the importance you're giving to Facebook.
I know a ton of people like to say that they can handle it, but just look at it closely: people get tagged so others can see the pictures they're in. You weren't tagged and feel left out that other people won't see that you're included. Why does that matter if you're seen by others on there or not? Especially by his extended family that may or may not even know you to begin with.