Ghost’s themes don’t natively support that much logic, but the underlying Handlebars engine does. According to this blog post, one can write a custom helper (in this case, to check the @member.subscriptionPlans.contains('tier1')
you mentioned). However, you’d have to go right into the Ghost source-code, and manually replace it every time Ghost is updated.
https://whitfin.io/adding-custom-ghost-handlebars-helpers/
You can probably write a script to insert it automatically each time, but either way this option will only be available to self-hosted users.
Those caveats aside, this setup seems quite promising. We could even replace the subscriptions page with custom code, ignoring the tier settings and hard-coding Stripe values directly, which would make for a more seamless experience (at least as far as the user is concerned—little will they know what’s going on behind the scenes! )