Thanks Julia, ok I should start to use BGyarmat then (or B-Gyarmat), I think that's also a common form. Writing in full Balassagyarmat every time is pretty long! The good thing about Fani's name is that Taub seems to be really quite a rare surname. I spotted a Simon Taub on my great grandfather's marriage entry in Budapest in 1873 as one of the witnesses, which leads to another, Hugo Taub. So building up the Taub family might be the way forward, There was also an intriguing Taub family I found on this site's databases at the 1848 census for Abaújszántó ,  2 Taub children separately entered, Fani (aged 9) and Rozsi (aged 2) without other family members, so I will have to trace that link back too.
Best
Emma