Creating an assembly line interaction and pausing a motion path

We want to create a stressful situation for our learners with an assembly line in which they must drag and drop items to their respective categories. Attached is a rough draft in which we already have the subtraction of "lives" working. However, we haven't been able to stop the motion path if the object has been selected. Can you lovely people think of a possible solution?

Google wasn't helpful, unfortunately.