I have web application node.js + vue.js. It currently has 2 tenants for each client and in future potentially there will be more clients and tenants. Each tenant has customized some functionalities on code level. What do you think is best approach:

• Create some base package and share it with multiple repositories
• Maintain one repository use feature flags to enable or disable functionalities
• Create one base repository and repository for each client and manually merge changes in core code
• use one repository with multiple branches for base and clients
• any other approach?
  What is your experience?

regards