How can I add an existing campaign to an automation?

[AutoComms]

I'd like to add an existing campaign to an automation.  For example, when a customer subscribes the automation triggers for them to receive a 'welcome' email, and thereafter i'd like an existing campaign workflow to be activated for that new customer.  

Any pointers would be really appreciated.

Thanks

[twjcbs]

Hi...

First, which app are you using for this? Perhaps is it klaviyo?