Pancaratna dasa: It seems to me over the years many devotees have had a try to understand this conversation with Srila Prabhupada which led to the July 9th Letter. The July 9th letter specifically deals with the now and not the future.
I am therefore taking the opportunity to give my understanding after thinking about this deeply for many years.
Satvarupa: Then our next question concerns initiations in the future, particularly at that time when you’re no longer with us. We want to know how first and second initiation would be conducted.
Prabhupäda: Yes. I shall recommend some of you. Not in future, now while He is present. After this is settled up, I shall recommend some of you to act as officiating äcäryas. “HDG is talking about now, officiating acaryas now, not the future. The above is not yet the answer to Satsvarup’s question. Srila Prabhupada is giving the initial system as to how things will work, while he is present.
Tamäla Krishña: Is that called Ritvik-Acärya?
Prabhupäda: Ritvik, yes.
SatsvarĂĽpa: Then what is the relationship of that person who gives the initiation and the…
Prabhupäda: He’s guru. He’s guru. “He is Officiating Acarya now but will be regular after SP leaves”
SatsvarĂĽpa: But he does it on your behalf.
Prabhupäda: Yes. That is formality. Because in my presence one should not become guru, so on my behalf, on my order… Ă„mära äjïäya guru haïä [Cc. Madhya 7.128]. Be actually guru, but by my order. “Because for formality one cannot be Guru while I am here so I order you as Officiating Acharya while I am here but after as Regular Guru.”
SatsvarĂĽpa: So they may also be considered your disciples.
Prabhupäda: Yes, they are disciples. Why consider? Who? “Those initiated now are disciples of Srila Prabhupada and those initiated in the future are disciples of the Officiating Acarya after HDG leaves”
Tamäla Krishña: No, he’s asking that these Ritvik-Acäryas, they’re officiating, giving dikshä. Their… The people who they give dikshä to, whose disciple are they? “The people who THEY GIVE DIKSHA TO, this means in the future when HDG is no longer with us, now HDG is answering Satsvarupa’s question”
Prabhupäda: They’re his disciple.
Tamäla Krishña: They’re his disciple.
Prabhupäda: Who is initiating. Are you talking about Me or the Officating Acharya. You said “the people they give Diksha To, whose disciples are they?. He is grand disciple.
SatsvarĂĽpa: Yes.
Tamäla Krishña: That’s clear.
SatsvarĂĽpa: Then we have a question concer…
Prabhupäda: When I order, “You become guru,” he becomes regular guru. That’s all. He becomes disciple of my disciple. That’s it. “Srila Prabhupada is actually ordering for Regular Guru but as he is still present, for formality, they will be called Officiating Acaryas”. There is a book with all initiated devotees names and the Officiating Acarya should send the new names to Srila Prabhupada to enter into that book,
“The initiated disciples book.” July 9th letter to All Temple Presidents”. This is to be done while HDG is present and the disciples are His and after he leaves the disciples are of the Officiating Acharya.
This is certainly my personal understanding, no doubt everyone has a right to differ.
Your humble servant
Pancaratna dasa Jaipur.

Interesting points. It is rather simple in your explanation. However it is not that simple if you want to interpret it. Thus the simplest explanation should win and you are the winner!
There is an even simpler explanation of the May 28th, 1977 conversation and the July 9th letter.
The July 9th letter presents a list of eleven disciples of Srila Prabhupada and refers to them as ritvik representatives of the acarya. The acarya is the actual initiator, so during Srila Prabhupada’s lifetime,
anyone initiated by himself or by a ritvik representative would be a direct disciple of His Divine Grace.
The term officiating acarya was introduced by Srila Prabhupada when he was asked about initiations that would be conducted particularly at that time when he would no longer be present. In other words,
when he would no longer be physically present, the initiators would then be Srila Prabhupada’s disciples acting as officiating acaryas and those receiving diksa from them would be Srila Prabhupada’s grand disciples. In order to act as an officiating acarya and for initiations to be effective
in linking the new disciple to the Vaisnava Sampradaya, the initiator would have to have all of the qualities of a regular guru.
Srila Prabhupada did not ever say that his disciples were already acting as officiating acaryas during
his lifetime because the word acarya would have indicated that his disciples were initiating disciples of their own. Pancaratna Prabhu has stated that “After he leaves, the disciples are of the officiating acarya,” with which I totally agree. The question is, “When will we start referring to those devotees who give initiation as officiating acaryas?” It is a very exalted position of service and the term specifically chosen by our founder acarya to designate those who would initiate disciples in ISKCON in the future.