She is said to work 16 hours a day
This is in fact a difficult construction for learners because actually the construction is not grammatical.
But it is complicated to show what has happened here. There are several things to explain.
a) The neighbour saw the boy break the window of the house across the street.
Here "to break" is followed by an accusative (object case) + bare infinitive.
English can turn such a sentence into passive:
The boy was seen to break the window.
b) The officer ordered the soldiers to attack.
Even if in other languages "the soldiers" would be seen as a dative object (indirect object)
and other languages would keep the dative object in a passive sentence
English does not say:
To the soldiers (it) was ordered to attack.
English shifted the dative to a nominative and says:
The soldiers were ordered to attack.
A passive that in other languages (e.g. German) is not possible. German would maintain the dative in the passive sentence.
This shift of case in passive sentences is a peculiarity of English, simply because dative (without "to") and accusative have the same form. And English does not care whether such a construction is a-grammatical or not.
So if you have a pasive sentence like
She is said to work 16 hours a day (1)
the "she" is a shifted case.
Actually is should be
"Of her it is said" to work 16 hours a day.
So you can't turn a sentence such as (1) into an active sentence according to normal rules.
Your assumption that the active is
A1: Somebody says to her to work 16 hours a day.
is simply wrong. That isn't the sense of the passive sentence.
The sense is:
People say of her that she works 16 hours a day.
I hope you won't get lost with my explanation. It is the first time that I try
to explain such a complicated thing such as passive sentences with shift of case.
And it is possible the native speakers don't agree with my view. And I might guess
that a lot of native speakers have lost the feeling for the fact that this passive contains
a shift of case.