FBAR for past years..???

My father lives in the states now but maintains a joint bank with my mother here in the UK. They are both UK citizens. Because of some inheritance their joint account was in access of 10,000 dollars for a few months about ten years ago. In this instance I am sure the account went over the 10,000 but it might have been over in other years.....If they did go over it was not by much maybe 13,000 or 15,000 or so...
They/we had no idea about the FBAR requirement and we are worried about how to proceed. Should we file it for that past years? Will they fine them? Any advice would be great.

Thanks,

NWKH

If you are a US person and have signature authority, you would report all non-US bank and financial accounts if the threshold is exceeded. They would report themselves if they are US persons and exceeded the threshold. They would in any case answer the question at Part III of Schedule B if they are required to file US income tax returns.