The Billa archive is published in JCS 7 (195x).

Sin-apla-eris<Assur-kasid 

8 eponyms are dateable to the activities of Sin-apla-eris<Assur-kasid at Billa, of which 1 is dateable to Adad-nirari and 7 to Shalmaneser: 3 very early and 3 in the sequence as late as Ellil-asared- thus covering a period of about 30 years from at least 1265 to 1237. The floruit of Sin-apla-eris thus almost exactly overlaps the reign of Shalmaneser – further [1] indicating that eponym Sa-adad-ninu is very late Adad-nirari 1. The only eponym, not identified in previously-discussed archvies,  is Istar-eris<Samash-aha-iddina. 

Eponym	Comment
Sa-adad-ninu	Adad-nirari 1 (through royal inscription)
Shalmaneser	Shalmaneser 1
Musabsiu-sibitti	Shalmaneser 1
Assur-kasid	Shalmaneser 1
Istar-eris<Samash-aha-iddina
Kidin-sin	Shalmaneser 1
Istar-eris<Sulmanu-qarrad	Shalmaneser 1
Ellil-asared	Shalmaneser 1

Istar-eris<Samash-aha-iddina  is clearly the brother of Ubru (eponym 1235) and Qibi-assur<Samash-aha-iddina  (eponym in late Shalmaneser or early TN1) – and is mentioned in eponym Assur-musabsi c1251.   Father Samash-aha-iddina is attested in eponym Musallim-assur.  This eponym is allocated one of the remaining early Shalmaneser 1 slots, although a late Adad-nirari 1 date cannot be excluded.  A TN1 date seems unlikely with the existing range of Sin-apla-eris.

Assur-kasid>Sin-apla-eris

4 eponyms are dateable to the activities of Assur-kasid>Sin-apla-eris at Billa. One is dateable to Adad-nirari; one to very early Shalmaneser. The other two eponyms (not discussed previously) appear dateable to Adad-nirari 1.  

Eponym	Comment
Assur-sad-nisesu	Definite Adad-nirari 1 (royal inscription)
Kidin-ilani	Probable Adad-nirari 1
Babu-aha-iddina	Probable Adad-nirari 1
Assur-kasid	Very early Shalmaneser 1

Note that letter Billa __ (dated in Assur-sad-nisesu) has a reference to prior eponym *-ilani – which would thus appear to be Kidin-ilani and to slightly precede Assur-sad-nisesu.

This is the only known occurrence as eponym Babu-aha-iddina.  This eponym has been identified with the important Shalmaneser 1 noble[2], Babu-aha-iddina<Ibassi-ili, although there is no proof of this. This would place the eponym occurrence earlier than the bulk of the Babu-aha-iddina correspondence.  In any event, the  four Billa eponyms referred to the reign of Adad-nirari 1 would appear to be at the very end of Adad-nirari 1 and thus there is no absolute chronological obstacle to this identification, although, equally, there is no necessity for it.