Bi-Directional Data Sync

I have a query on bi-directional data sync. The scenario is, that we have ERP software running on a local network which is developed in PowerBuilder and the database is SQL Anywhere 16, Also, we have our cloud software which is developed in .net6 and the database is Azure SQL. And also we have a Middleware developed on .net which interacts with our API and local DB. After an operation like Invoice generation, we need to keep the quantity of a product accurate the same as local DB and cloud DB. Whether the operation happened in the cloud or local network. Please share your thoughts.