I have a web application maden with struts2.2.x

I'm adding asynchronous function for refresh only 2 fields (says F1, F2) of the main jsp. The total fields are 50.
Even F1 F1 are inside a larger FORM for total submit after.
I Use the plugin for jquery 3.3.1.
The F1 F2 fields are inside a DIV tag, who is the TARGET for the asynch submit.
The asynch. submit is ok, with tags jquery <sj:submit> or <sj:a>
the problem is that in the asynch. jsp answer the fields F1 F2 are added to the main, so are double and not refreshed.

The questions :
-- how is the struts result definition for "asynch" part ? the same main jsp ? Or a new jwp wiht the two field only ?
-- is it possibile annidate form sync (total submit, 50 fields) with inner form async.(for refresh F1 F2) ?

thanks Nicola