How do I pick another family while I already picked one?

Hello I'm Greg and I'm still trying to get familiar with C2. My question is I don't know if it's possible to pick one family as a sub-event while the parent event has picked one. The is because I want to pick some sprite(s) according to the picked parent sprite's instance variable:

I do that is because I want to allow user switch weapons, so that the bullets should be switched, too. However, according to the articles about picking I have seen, the SOL of sub-events would be restricted to what the parent selected, although I don't know whether that's the reason I did that fail (the picking Bullets didn't work). So I wonder if there is a better way to do that? Or I should change my whole pattern?

You would do a "Pick all" to get the whole list again, and then your specific pick.

Could you elaborate more please? Since I tried to do that as an sub-event of the parent event, but it picked nothing:

I removed the deeper sub-events of the picking all to clarify the case (they won't be triggered at all). I also tried to put the picking all as the top-most event. It works but the it's sub-events won't work.

I think you need to clarify what you want to do. If there are no bullets created, then you can't pick any, and that seems to be the case. Looks like you are confusing what UID will do for you. If you want a certain bullet type, you need to identify the type, not the UID (that I assume you are seeing in the GUI).