Merge multiple state files into single

Hi, I have a terraform source code for creating a GKE cluster and two node pools from a single file (gke.tf).
Once cluster is created, we have a requirement to add new node pool from another file (nodepool.tf). What is happening is we are getting two state files.

  1. state file with cluster and original nodepool details
  2. state file with additional nodepool
    I want third nodepool details to be present in first state file. Is there a way to merge two state files or to add 2nd state file to first one. We are using terraform workspaces for this.