Spotify does not have the power to lock your credit card or paypal account. Account bans might happen and I have seen E-Mail screenshots of people who got banned. I am not sure if they would take down an entire set of family accounts.
If you care about the content of your Spotify account (playlists, listening history) you should not use it for piracy. Just create a new one. If you are fine with 160kbps OGG files, you dont even need a paid account.
Do not create Spotify accounts with trash mail addresses, they may work at first and get banned the next day (happened to me after I created some accounts for scraping their API).
You can also export all your Spotify data as a precaution (GDPR export from the account page, they send you an email with a link to a zip file after a couple of days).
You dont need a second computer, just replace the drive with an empty one.