Good Morning @huixin_liu. This is a very common question.
The short answer is that there is no way of creating a template with multiple signatories directly; you have to write a workflow to ‘collect’ the signatures. Here is an example of how to do this when there are just two parties involved: Learn the fundamentals of DAML online: The propose/accept pattern
The concept can be extended to multiple signatories.
Once you’ve done this, you will exercise multiple choices through the navigator to collect these signatures; each choice will require a different participant, so you will need to re-login between steps.
Hope that helps!