One of the two Familiant records (from Westetz) indicates that Nathan's first wife was Rachl (unbekannt), and I would presume Rachl to be Abraham's mother. https://vademecum.nacr.cz/vademecum/permalink?xid=64ee93d5-ab5c-4bb...
However, there are several inconsistencies between these Familiant records and other records that appear to belong to this family. I think we need to take a careful look to be sure we can explain the discrepancies and are not conflating two or more families with similar names.
1. The two Familiant records indicate that Nathan married Barbara "Sak[in]" rather than Sinek.
2. The two Familiant records indicate that Abraham married Barbara Reiner/Rainer rather than Rosalia Pollak.
3. There is a third Familiant record for a Nathan Kohn in Budislav/Jungwoschitz whose father was allegedly Jakob rather than Isak (as in the other two records). https://zayt.org/collections/jewish-familiant-books-1811-1848-redux... The comments on the right side of the page do appear to match with the other two Familiant records, but the date of the father's marriage permission (1784, rather late!) and name of Nathan's father don't seem to match for this family.
I will look into it more later.
