I'm not sure if it is what you want, but I did something that may help you.
In my case, the rules change depending on some business rules. For example, in one scenario my form has fields A anb B required, but in another, it has fields B and C required.
I didn't find a way to recreate the bean that extends the DefaultRulesSource, because it is registered by another bean that aplyes the rules on the forms.
So, the solution was to change the existing rules.
First, take form context the DefaultRulesSource bean.
In the context:
In your class, call that:
<bean id="rulesSource" class="br.com.xxx.ValidationRulesSource" />
Now you have access to the bean tha has all your rules.
ValidationRulesSource rulesSource = (ValidationRulesSource) Application.instance()
The rules can be grouped by the bean class. Using this information, the framework know waht rules to apply to each form.
You can get the rules os a specific class like that:
So, you can create new rules and set them to the rulesSource, like that:
Rules rules = rulesSource.getRules(YOURBEAN.getClass());
Do this before construct the form and it should work.
List<Rules> regras = new ArrayList<Rules>();
// add your Rules to the list
I hope this can help you.