Question:  Can you have a Template or task list that is dependent upon completion of prior tasks or projects?

Example:  Looking to have a project with Tasks and milestones revolving around the design and quote of a product.  I then want another template to create if and when a Purchase order is received for that item.  

Idea: looking for way to have projects in the system but not look like they are all uncompleted.  Many quotes will never actually have Purchase Orders initiated.