Does anyone know how to solve this? I

Re-generate your vector store with all the docs together, I have not heard of merging the stores but it should be possible

You can get all the nodes from your first index like this:

1. If it is a local vector index:

nodes = index.docstore.docs

1. If you have used third party vector store then you will need to use the vector store client to fetch all the nodes from that store.

once you have all the nodes , simply insert those nodes into the second index.

Let me try