Ability to propagate changes from Blueprints + support dynamic templating per stack

We're managing a multi-tenant infrastructure with 40+ stacks generated from Blueprints. While blueprints are a great starting point, the current model becomes difficult to scale as we grow.

Once a stack is created, it's disconnected from the Blueprint — so if we need to update something across all stacks (like add a config flag or a new file), we have to do it manually or build internal tooling to handle it. This is both time-consuming and error-prone. What would be helpful:

1. Blueprint-linking after creation

   • The ability to apply changes from the Blueprint to existing stacks when needed is like syncing changes downstream.

2. Templating system for dynamic config

   • We'd love to be able to define shared files (like a config file) in the Blueprint and inject stack-specific values dynamically, maybe via a map (e.g. stack ID → values).

This would help us keep stack behaviour consistent while still supporting tenant-specific differences.

Why this matters:

We're growing quickly, and the manual effort to maintain stack configurations is already a burden. The more tenants we onboard, the harder it becomes to keep everything in sync, which slows us down and increases the risk of errors. Having more tooling here would make Spacelift even more powerful for teams like ours who are scaling infrastructure as a platform.