The contact information will be available through the NSA. I have sent a couple of letters in the past and did get replies.
We know Baha'u'llah confirms both the Bible and Quran stories, I have posted the Letters and a provisional translation of a Tablet of Baha'u'llah.
It appears this will need to be cleared up, as it appears the people who have written those letters, have not known what Baha'u'llah offered.
As to whether Ishmael or Isaac were to be sacrificed, here are some letters
(Forum post from Wilmette course)
1) "As to the question raised by the Racine Assembly in connection with Baha'u'llah's statement in the Gleanings concerning the sacrifice of Ishmael; although this statement does not agree with that made in the Bible, Genesis 22.9, the friends should unhesitatingly, and for reasons that are only too obvious, give precedence to the sayings of Baha'u'llah which, it should be pointed out, is fully cooroborated by the
Qur'an which book is more authentic than the Bible, including both the New and the Old Testaments. The Bible is not wholly authentic, and in this respect is not to be compared with the Qur'an, and should be
wholly subordinated to the authentic writings of Baha'u'llah."
Letter written on behalf of the Guardian to the NSA of the US and Canada, July 28, 1936,; Baha'i News,
No. 103, p. 1, October 1936.
2) ...the reference to Ishmael is correct, although it disagrees with the text of the Bible. The Qur'án too corroborates this statement of Bahá'u'lláh, and as this book is more authentic than the Bible, it is obvious that it should be given precedence over the Jewish and Christian Holy Scriptures, which cannot be considered as being wholly authentic.
(From a letter dated 7 March 1938 written on behalf of Shoghi Effendi to an individual believer)
3) The Guardian confirms that the record in the Qur'án and in the Writings of Bahá'u'lláh, that it was Ishmael, and not Isaac as stated in the Old Testament, whom Abraham was to sacrifice, is to be upheld. In one of His Tablets 'Abdu'l-Bahá refers to this discrepancy, and explains that, from a spiritual point of view, it is irrelevant which son was involved. The essential part of the story is that Abraham was willing to obey God's command to sacrifice His son. Thus, although the account in the Torah is inaccurate in detail, it is true in substance.
(From a letter dated 19 July 1981 written on behalf of the Universal House of Justice to an individual believer)
This is from a provisional translation
"...... Consider: all those who believe in past Scriptures
[7] think of Isaac as the Sacrifice; likewise, the people of Qur’án
[8] confirm this station for Ishmael. It is clear and evident to every possessor of insight and every religious person that no one was, outwardly
[9] sacrificed; all agree that an animal was sacrificed. So, ponder upon this: Why is it that a person who hath gone to the altar of sacrifice for the Beloved and yet hath come back [alive], is adorned with the raiment of ‘Sacrifice of God’ and accepted
[10] as such? There is no doubt that this is so because of the Word of God. Therefore, the criterion
[11] for the manifestation of all names and for confirmation and fulfillment of all stations is dependent upon the Word of God.
[12] Likewise, there is no doubt, that the Inaccessible, Unknowable [God] doth not talk as He is, and hath always been, sanctified from such conditions; rather, He speaketh through the tongue of His Manifestations.
[13] Thus the Torah issued from the tongue of Moses. The same is true of other Holy Scriptures: all were revealed by the tongues of Prophets and Messengers but, the real Speaker
[14] in all these Holy Books is the One true God.... It is now, therefore, established and confirmed that the station of ‘Sacrifice of God’ was, according to past Books,
[15] given to Isaac by Abraham and that very same station is, according to Divine Revelation, Ishmael’s in the Qur’ánic Dispensation.
[16]"
Tablet to Hájí Mírzá Kamálu'd-Dín
Regards Tony