Yes. You can choose to have multiple autoresponders subscribed to all new clients. When you edit or create an autoresponder (in COMMUNICATE TAB > Autoresponders), in Tab 3 of the wizard titled "Select Subscribers" you can check the box to "Subscribe all new clients to this autoresponder" (see screenshot below).
Anytime you switch someone in your list to active client, you will be presented with the option to subscribe them to the autoresponders that has this option checked. You can also subscribe someone manually to specific autoresponder series by going to their Profile (in CONTACTS TAB > Contact Name > Profile tab > Autoresponders section), checking the box in front of the autoresponder series, and saving.