Hi ,
I believe this is more related to refresh in client activity on the entity. While going to next page make sure to build your association and keep refresh in client yes.
If you want to store un filled form data means a draft copy even if user stops in between then commit the objects . The only purpose to commit the object at the final save refresh in client will help to keep the filled fields and associations alive till to the last step.
Hope this helps!
Thank you.