I am trying to update a field inside row action popup window using action "update field on row" added to button click. The problem is that it updates all the rows with the updated value whereas the desired result should be only updating the current row's field.
There are several strategies you can use. One option would be to read the row into a separate model and associate this new model with the field editor. On Save, you will need to re-query the relatedShippings model to pick up the changes.
I think the basic problem is that somewhere in your action sequence tied to the row action - you are losing context. This most often happens when you create a new row. So if you can put your field update action first in your action sequence the problem should not occur.