The easiest way I can think of to do this is by using Process Flow logic instead of a separator. (I find it difficult to customize the separator without using lots of custom code.) In the case of my example I made a Processor, and a Process Flow that creates tokens based on the OnProcessFinished trigger to simulate a separator.
Then I just created a simple subflow logic that parses through the contents of your packed objects, and moves the specific item to a different location, but keeping your other items packed as you designated.
I've attached the example model below, feel free to use any of it that is helpful to you.
separator.fsm