Hi Slavko,
I haven't tested these ideas, but they could work:
Preventing updating:
You could set up an editable restriction on each column in which you check whether there's a child row in the other item list.
Preventing deletion:
I would disable the delete button in general. Instead you could add a picker to where the user can mark the rows to delete. On save/path transition you can check whether it's save to delete the row. I don't know your situation but maybe it's not even necessary to delete the row. I prefer to mark the rows as invalid/not necessary.
Without knowing the circumstances, I would switch to a two step approach unsing the wizard step option.
Best regards,
Daniel