thanks for reaching out! this is a case that we're thinking about improving -- providing better separation between activity in multiple github organizations
i can confirm that in your current setup, your activity (submits/reviews/merges) will only count towards the org they happen in, so cinder will not be billed for your personal use of graphite
unfortunately we haven't added support for installing the slack integration on multiple workspaces yet, but this is something we're considering soon!