Vaadin flow add or force changed bindings, from bakery example

Hi,

I have a form with some fields binding like documentation says, but need some solution to mark or changed binder on another field, hidden or transient.

I need some like this because, I have a form make use of bakery example, with attachments that are preparing, but not saved on database until save the principal entity, and the problem it’s that when add a attach but NOT update rest of fields, binder not launch write.

Anybody can give me help or any alternative?

Thanks