Siemplify recommends making a final decision about High-Availability(HA) support before first deployment. This is because HA deployment contains many components and complex processes.
Having said that, a customer can upgrade the system from single-node/all-in-one deployment to HA deployment. The upgrade process involves building a new environment with all components as a parallel environment according to the deployment guide and copying data and configurations from the existing all-in-one environment to the new HA environment. This process should be carried out by the Siemplify Deployment Team. Note that this upgrade process to HA requires the down-time of the system.