As we have seen many times, two brothers playing in the same international team is a fairly regular occurrence but not so common is three brothers playing together at the highest level.
Back in 2012, Slovenia fielded three brothers, with Domen, Rok, and Grega Bohinc all taking the field in the ICC Europe Division 3 tournament in Tallinn, Estonia.

The brothers all played in matches against Estonia and Bulgaria, with Slovenia finishing second in the competition.
A rare feat, but it has happened before, most notably when WG Grace and his brothers Edward and Fred played a Test match against Australia in 1880. In 1892 we had the unique situation of three brothers playing in the same Test match but on different sides with Frank Hearne (South Africa) in opposition to George and Alec Hearne (England).
The most recent incidence of it happening in a Test came in 1969 when Mushtaq, Sadiq and Hanif Mohammed played for Pakistan against New Zealand.