How do 2 junior devs manage to rewrite the entire product while also meeting the ongoing goals of the business? You're trying to spec features on a moving targ

How do 2 junior devs manage to rewrite the entire product while also meeting the ongoing goals of the business? You're trying to spec features on a moving target. Even if they were able to do 50% time on the rewrite you'll never actually get to feature parity. The only viable plan, unless the company has an appetite to triple the dev headcount, is to set an expectation that features will have an increased dev time, then as you spec new features you also spec out how far you will go into the codebase refactoring what the new features touch.