You can statically map a configuration to a company at any time.
The advantage of statically mapping a configuration to a company is that it saves time and you can use the intercompany function.
How to assign a client to the indexing definition: Configure the index definition for the Dynamics 365 process
You can export the configuration of your ECM company with the statically mapped company under Maintenance and import it again in another system.
For more information see: Where do I specify the company?