two things...
1.
you should break the form up from the user interface perspective and use one form bean that is placed in the session to gather and/or display the data. when going from page to page, gather the data, but not submitted to the back end (DB) until the entire form is completed.
the individual page with the same form bean declarative validation can be achieve using the DynaActionValiationForm type (NOT DynaValidationForm type) which allows for you to map action path instead of form name to the validation.xml's configuration.
in essense, assuming you're breaking the form into 5 pages, you'll have 5 action paths (page1.do, page2.do, page3.do, etc.) that are mapped to the same form-bean with the scope='session'. in your validation.xml, you can then define the rules for each page somewhere along the line...
2. for the '1 to many' details, you need to use indexed properties to handle the data (see the struts user guide).
be sure to use the struts-html tag lib to display your form. the use of JSTL tag lib (core and format) is highly recommended.