How to merge databases in Neo4j 4

Hi,

Very happy to join the community.

I understand in Neo4j 4, we are able to switch to another database in Neo4j Browser. My question is how can we merge 2 or more databases? Say I have A.db, B.db, and C.db, how can we combine A, B, and C to generate a single database?

Appreciate your help!

Shuai