It is completely driven by struts-config in your case(since you have only 1 form and 1 JSP).
Firstly, to me i do not use the action class as a model part (debatable) instead i use it as controller (in case of earlier versions of Struts2). Just to minimize the number of action classes and struts mapping.
However you can achieve this in 2 ways
1. You can have more than one action mappings in struts-config with the same form. And while submitting the form from JS you can mention the URL corresponding to your action classes
2. On submit from JSP, you can always direction to one action class and from their based on requirement, conditionally forward it to other action classes.
Have Fun with Java
little,little.. little by little makes a lot..