Determine family minhag

I am trying to determine my family minhagim and nusach. No one in my family knows for certain bcause no one has been observant for many many years. I know what towns in Poland/Lithuania my father’s father and grandfather came from. Is there anything I can/should do to determine minhag and nusach? I have my father’s mother’s father’s siddur from Poland and it is sepherad. My father’ s mother and father (and their fathers) both came from the same town (but there may have been more than one shul). The town is now Augustow, Poland (it was in Lithuania when they left).

Try to find someone that would tell you the standard custom of that town (I don’t think that will be an impossible quest) and you can assume that was your families Nusach. If it is a difficult task to change what you are use to for many years and it will ruin your Tfilah – you can stick to your old Nusach.