Curiouser and curiouser. What year did you file? Surely it was not for 2014 as the US Treasury has not yet published the official 31st December exchange rates yet; and no other exchange rate is permissible; so a 2014 FBAR would be too early.
I didn't use an exchange rate. I have a general idea of the value of the estate and know that my interest in it will be well over $10k using a sensible exchange rate, but I don't know the final value, so when given the chance to answer "I don't know" I took that option.
The solicitor will know the account balances if asked; so once you have this data from the solicitor and the official exchange rate is published, you can file an amended FBAR with the correct data.
He has provided estimates, but there are still bills to pay and some shares to sell and the house to settle. The estate was in probate during 2014 and will settle in 2015. So I did not feel comfortable giving a value in 2014 and presented with "I don't know" as an option is seemed the best option. I will give the actual value in 2015 using the appropriate exchange rate.
Don't forget to file a Form 3520 with your income tax return for the inheritance.
I received part of my bequest from the estate in December that was well below $100k so won't file a 3520. I will get the rest of the inheritance in 2015 and if it exceeds $100k I will file the 3250.
If the Treasury wants more information I will gladly provide it if they contact me. I'm probably one of the few US citizens that actually bothered to report an foreign inheritance and probate estate on an FBAR in 2014.