This is what I am able to come across about the four representatives.
THE FOUR REPRESENTATIVES:
Uthman ibn Said remained the
“representative of the Hidden Imam”
for a number of years. In all that
time, he was the only link the Shia
had with their Imam. During that
time, he supplied the Shia community
with tawqiat, or written
communications, which he claimed
were written to them by the Hidden
Imam. Many of these
communications, which are still
preserved in books like at-Tusi’s
Kitab al-Ghaybah, had to do with
denouncing other claimants to the
position of representative. In fact,
many people had come to realize
exactly how lucrative a position
Uthman ibn Said had created for
himself, but Uthman ibn Said blocked
their efforts by the tawqiat which
called them liars and frauds. The
Shia literature dealing with Uthman
ibn Said’s tenure as representative is
replete with references to money
collected from the Shia public (i.e.
Khums).
When Uthman ibn Said died, his son
Abu Jafar Muhammad produced a
written communication from the
Hidden Imam in which he himself is
appointed the second representative,
a position which he held for about
fifty years. He too, like his father, had
to deal with several rival claimants to
his position, but the tawqiat which he
regularly produced to denounce them
and reinforce his own position
ensured the removal of such
obstacles and the continuation of
support from a credulous Shia
public.
Abu Jafar Muhammad was followed
in this position by Abul Qasim ibn
Rawh an-Nawbakhti, a scion of the
powerful and influential Nawbakhti
family of Baghdad. Before succeeding
Abu Jafar Muhammad, Abul Qasim
an-Nawbakhti was his chief aide in
the collection of the one-fifth taxes
(i.e. Khums) from the Shia. Like his
two predecessors, he too had to deal
with rival claimants, one of whom
(Muhammad ibn Ali ash-
Shalmaghani) used to be an
accomplice of his. He is reported in
Abu Jafar at-Tusi’s book Kitab al-
Ghaybah as having stated: “We knew
exactly what we were into with Abul
Qasim ibn Rawh. We used to fight
like dogs over this matter (of being
representative).”
When Abul Qasim an-Nawbakhti died
in 326 AH, he bequethed the position
of representative to Abul Hasan as-
Samarri. Whereas the first three
representatives were shrewd
manipulators, Abul Hasan as-Samarri
proved to be a more conscientious
person. During his three years as
representative, there was a sudden
drop in tawqiat. Upon his deathbed,
he was asked who his successor
would be, and he answered that Allah
would Himself fulfil the matter. We
wonder: could this perhaps be seen
as a refusal on his part to perpetuate
a hoax that had gone on for too
long? Abul Hasan as-Samarri also
produced a tawqiat in which the
Imam declares that from that day till
the day of his reappearance he will
never again be seen, and that anyone
who claims to see him in that time is
a liar.
Thus, after more or less 70 years, the
last “door of contact” with the Hidden
Imam closed. The Shia term this
period, in which there was contact
with their Hidden Imam through his
representatives-cum-tax-collectors,
the Lesser Occultation (al-Ghaybah
as-Sughra), and the period from the
death of the last representative
onwards the Greater Occultation (al-
Ghaybah al-Kubar). The Greater
Occulation has lasted for over a
thousand years.