var table = project.Tables["data"];//таблица
int sortByCol = 2;//колонка, по которой сортировать. отсчет с 0
int rowLeave = 3;//сколько строк отступить сначала
//заполняю табличку тестовыми данными
table.AddRow(new[]{"asd","fe","edf","dg","db"});
table.AddRow(new[]{"db","df","db","dfb","dfb"});
table.AddRow(new[]{"sa","asd","dbfs","dfbds","dvfb"});
table.AddRow(new[]{"we","we","6","we","we"});
table.AddRow(new[]{"sd","w","1","qwe","e"});
table.AddRow(new[]{"sf","sdf","3","s","sdf"});
table.AddRow(new[]{"sdf","sdf","2","sdf","sdf"});
table.AddRow(new[]{"sdf","1","5","2","2"});
table.AddRow(new[]{"1","2","4","3","hjgsd"});
//
var items = table.GetItems($"{rowLeave}-end", true).Select(x=>x.ToArray()).ToList();
items.OrderBy(cols=>cols[sortByCol]).ToList().ForEach(row=>table.AddRow(row));