I think the seated woman is Pauline Neville-Jones, who was leading the UK's delegation. She was a senior civil servant (director of the Foreign and Commonwealth

I think the seated woman is Pauline Neville-Jones, who was leading the UK's delegation. She was a senior civil servant (director of the Foreign and Commonwealth Office) rather than a world leader. I think the woman in green leaning over the table is some sort of aide rather than a person of power in her own right. See e.g. the picture here https://www.aljazeera.com/news/2020/11/20/dayton-25-years https://www.aljazeera.com/news/2020/11/20/dayton-25-years where she's apparently sorting out a document for the president of Bosnia while others to her left and right are doing likewise for the presidents of Serbia and Croatia.