Thank you, Alleymom, for the additional information! Very helpful.
I don't think Sack was misrepresented in this instance as the WT's note 9 referencing him is directly in connection to the anomalous dating of BM 75489 which places Neriglissar's reign a fair few months before the end of Amel-Marduk's. BUT the article is clearly muddying the waters. As you pointed out, you can't have it both ways. You can't argue for overlapping reigns in one paragraph, and then in the very next paragraph argue for gaps or discontinuous reigns.
P. 24 of the article:
"What do the documents show? There are further discrepancies in the transition of one king to another. For example, the documents show that Nebuchadnezzar II was still ruling in his tenth month - six months after his successor is assumed to have begun reigning. 8 A similar discrepancy exists with the transition between Amel-Marduk and his successor, Neriglissar. 9 [the note re: Sack and BM 75489]
"Why are these discrepancies significant? As mentioned earlier, gaps in the history documented by the Babylonian chronicles suggest that we may not have a continuous chronological record. 10 [the note re: Dougherty and Belshumishkun]
Regarding these tablets mentioned in notes 7, 8 and 9:
BM 80920 - said to be dated to Amel-Marduk's month 4 is incorrect - it's actually dated to month 7;
BM 58872 - dating to month 5 is correct;
BM 55806 - said to date to Nebuchadnezzar's year 43, month 10 is incorrect - in fact the year number is partially erased and highly uncertain, and the month number might be 5;
BM 75106 - said to be Amel-Marduk, month 7 is also wrong - it is actually month 4;
BM 61325 - month 10 is correct and is anomalous.
BM 75489 - Neriglissar's accession, month 2 is correct and, as mentioned above, is also anomalous.
For more details about these corrections, see HERE.