I have had to do similar thing before with ticketing systems and admin areas based off of data form separate list. One of the best methods I have found is with your list 1 and list 2 is as follows:
When a user creates a list item in list 1, have a workflow create an
item in list 2
As part of list 2, create a meta column to capture a reference to the list item in list 1
Name it trackerID or something to help you remember
In your workflow that creates the item in list 2 when the list 1 item is created, set the trackerID in list 2 to the list item ID in list 1. This will create an artificle one-to-=one relationship between your two list.
your list items are now connected
Now you can create logic in workflows between the to list and link them.
When a user updates an item in list 1, I want to update fields 1, 2 and 3 in list two when trackerID eq list 1 item ID.
You can go the other direction as well. Now you can pass data back and forth between the list and also update data from the second list in relation to the list item in list 1.
User 1 has used a tool and it is updated in list 1. If useage of the tool in list 1 > 10, update list 2 meta data about the tool where list 1 item ID eq list item 2 trackerID
I hope this makes sence to you. Thi sis a great way to simply and effectivly link SharePoint lists items together. You can keep goin gwith this logic through several list and have them all connected to the original. I have systems that use 20 lists and I can always go back and forth at any poin tin my pogic using this method. Good luck!