https://www.familysearch.org/ark:/61903/3:1:S3HY-XC5W-5KJ?i=24&...
I have no clue what evidence there might be for him being the father of anyone.
Hi - just noticed your comment which I missed at the time. I'm not sure how he was placed as Mordechai's father in the first place. in 1827 there were Nathan and Mordechai who were similar ages and Abraham who appears to have been a generation back. I'm not sure at this point whether that was a presumed relationship as a result..I know I tracked down a Hebrew inscription Israel ben Mordechai that confirmed Ignaz and Marcus were son and father but no recollection of finding anything similar for Abraham.