Multiple target drag and drop using pick many - or something else?

I have five targets. I have a list of items which can all be dragged onto the targets - five of them will be correct if dropped on ANY target - three will be incorrect. The user has to pick the correct 5 and drop them on any of the targets.

I've tried to score this in two ways.

1) Added the trigger to 'correct' items: change state to 'dropped correct' when user drops shape on (any of 5 targets).

2) Added the trigger to 'incorrect' items: change state to 'dropped incorrect' when user drops shape on (any of 5 targets).

Then I get stuck marking it. The submit button wants to submit an interaction that doesn't exist - I'd like to define one that checks all the correct items are in 'dropped correct' state, for example - but perhaps I'm misunderstanding how interactions work and that's not something you can do. Google isn't helping me on this. So I tried approach 2:

1) Convert to Freeform 'pick many'

2) Change triggers on all items to: change state to 'selected' when user drops shape on (any of 5 targets)

3) Entered all the items into the choices list and checked the correct 5 as correct.

Assuming that the interaction looks at which items are in state 'selected' and scores correct if they match those in the list. Since I've told the items to change their state to selected when they're dropped on a target, I thought that should work.

Only the items won't change state when dropped, only when clicked.

Can anyone help me figure out how I should do this? I realise I'm missing some basic understanding of how interactions work (why can't I customise a pick many to check for a different state to 'selected'?!) or trigger priority (drop state change not overriding click). Sorry for all the words :)