Rerouted are definitely more work than usually anticipated, unless most or all of the original team is available. The other option to figure it out again from

Rerouted are definitely more work than usually anticipated, unless most or all of the original team is available. The other option to figure it out again from scratch has its own issues. If existing business logic works and has been hardened, it can be worth looking at wrapping it an API instead of rewriting and reimagining from scratch.