Step 1:
Create new folder on your local drive for your new client site.
Step 2:
In Dreamweaver set up new site ... Site ... Manage Sites:
Step 3:
Under local root folder, point to your newly created client folder.
Step 4:
Then click on testing server.
Step 5:
For Server Model select PHP mySQL.
Step 6:
For Access, make sure it says Local/Network.
Step 7:
For Testing Local Server, point to your new client folder.
Step 8:
Last, you need to set up your URL prefix. Launch MAMP.
Step 9:
After open, click open start page.
Step 10:
Delete everything after the crazy 8888's in the URL.
Step 11:
Navigate to your client folder and copy out that URL.
Step 12:
Copy the URL and paste it in the URL prefix under the testing server tab.
Step 13:
Create either a phpinfo file or other .php file so you can test if its working by opening it up and previewing it.
Step 14:
Now you'll be able to select your multiple client folders in dreamweaver in the files tab.