Business needs change. Your hire's focus can change with them.
Scope shifts (same role)
If the shape of the work drifts (say your EA starts doing more inbox triage and less travel), we re-train in the background. Your hire keeps their account history and relationship with you; only the focus shifts.
No new contract, no billing reset. Just mention it to your Customer Success Manager.
Role changes (different role)
If the work fundamentally changes (e.g. you want to swap your EA for an SDR), we match a new hire with the new role profile. The handover is coordinated so you don't lose continuity, and billing transitions smoothly on the same invoice cadence.