1. Use electronic signature software: Many electronic signature software provide multi-person signature function. By adding the electronic signatures of all signers to the same document, the signatures can be integrated.

2. Use digital certificates: Digital certificates can be used to verify the identity of signers, so you can integrate signatures by adding digital certificates of all signers to the same document.

3. Use cloud storage: upload the document to the cloud storage service, add multiple electronic signatures to the document, and then save it.