How to use:
  1. Run Chrome with the command-line flag
    --use-first-party-set=https://fps-member1.glitch.me,https://fps-member2.glitch.me,https://fps-member3.glitch.me
  2. Click below to set cookies, then come back here.
  3. Observe that SameParty cookies respect First-Party Set boundaries.
Click here to set cookies.

Member 1

Cookie header: