In your .gpg-id file, simply list the keys you want to encrypt for on separate lines. Every file below that .gpg-id file in the directory hierarchy will be encrypted for any of those keys to unlock.
Also you can re-init any time you want, listing multiple keys. This will go through all your passwords and re-encrypt them for each of the keys listed. That's how I got my phone set up with access (with its own locally-generated private key).
If you want more granular key strategy, look at gopass [1], which is a pass-compatible binary that gives a little more granular control over key usage (IIRC), and is written in Go.
In your .gpg-id file, simply list the keys you want to encrypt for on separate lines. Every file below that .gpg-id file in the directory hierarchy will be encrypted for any of those keys to unlock.