@hp100 , Since the FBAR reporting is based on the last day of the year, using the YE exchange rate should not pose an issue . The basis of the inherited property is generally based on FMV at the time of death of the decadent or soon thereafter and so using the FMV on 09/02 is close enough. From your post it sounds like there was an estate established ( probably with pour-over from the trust) and therefore the transfer of the house was recorded to you on 09/08. Assuming that all these are during the year 2020 and you sold the property during the year, the gain seems a bit surprising. If indeed this is the case and true then the establishment of basis on 09/02 would become suspect --- 5 months after death ( generally basis is assumed to move rather slowly).
Because this is a distribution from an estate there may be no requirement for the form 3520 but I do not know the whole scenario, nor do I know the country.
As far as the exchange rates used , it should pose no issue -- generally one uses the dollar of the day either market or what your bank gave you. Keep good records in order to sustain an audit (if)
