Complex sentence: Members of the association are the three municipalities of Livno Canton-Bosansko Grahovo, Glamoč and Drvar, and are currently negotiating with the leaders of Bosanski Petrovac in the Una-Sana Canton, so that the municipality has become a member.
Split into simpler sentences: Members of the association are the three municipalities of Livno Canton-Bosansko Grahovo, Glamoč and Drvar. They are currently negotiating with the leaders of Bosanski Petrovac in the Una-Sana Canton, to include it as a member.