In some cases, you may need to create custom intermediate protobuf messages, especially when facilitating communication between Substreams handler modules or storing additional data in stores.
Place these protobuf files within your Substreams package, such as ./substreams/ethereum-template/proto/custom-messages.proto. Be sure to link them in the substreams.yaml file. For more details, refer to the substreams manifest documentation or review the official Substreams UniswapV2 example integration.
