My ex won’t stop using my address to commit state healthcare fraud since she lives in another state, how to stop her/turn her in?

As the title said it’s been over a year since we broke up but she and her baby daddy are still using my address to get our state’s medical (Molina Health in WA state) The first thing to know about my ex is she absolutely loves to lie so she had a grand ole time calling the animal control and city ordnance people when we broke up last year, so it’s not a shock she’s lying to Molina. She even came to my house a few months after we broke up to brag about the fact that she was pregnant with a boy, her boyfriend makes over six figures mining, and they’ve already moved to another state and I know for a fact they live in Idaho because she has a job two hours away into Idaho. So in no way do they actually need WA state medical, she’ll just do anything to not have to spend money. I’ve sent emails to fraud departments and called and left voicemails but they keep on getting their medical sent here so seems like that hasn’t worked. I left a note for the mail man but we still get their mail so I bought a locking mailbox so they won’t be able to go through our mailbox anymore and will be going to the post office in person on Monday. Is there anything else I can do or another subreddit that might be more appropriate? Thank you for taking the time to read this