Thanks for your advices.
Maybe the better way is to design some different prototypes and to see what they like more.
At least for child rows, make sense to have another form.

>>This is true.
>>For this I think to have a separate set of small buttons, specific for detail rows adding/editing, located on form. I've done something like this, using a modal floating form without title. Buttons on main toolbar will be used only for master table records.
>>Another thing that I observed is that they like the idea of having a double role button , Save + Add new, when they add data.
>>Still don't know what is the best way, that's what I've started this thread, I don't have much experience
>> with many users.
>
>Of course you can have separate buttons. The problem is the shortcut keys: the user will need separate shortcut keys for parent and child. Also, if your main toolbar only creates a parent record, this will be confusing: at some moment, the user will expect to create a child record, but a parent record will be created instead. Of course, the user will get accustomed in the long run.
>
>With separate pages, or separate forms, the user will have one single interface for parent, child, grandchild...