Five hundred people were selected by computer Wednesday from some 66,000 people who had applied for a chance to meet their families living in North Korea, the first step in what must be a gut-wrenching wait for the families separated by the Korean War to see if they will be among the 100 people chosen from South Korea to meet their families in the North at next month’s reunion.

The first reunion to be held since the last one was held in February 2014, the agreement on the inter-Korean family reunions was reached after nearly 23 hours of non-stop negotiations between the Korean Red Cross and North Korea’s Red Cross. The two sides hammered out a plan for a reunion of 100 families from each side to take place Oct. 20-26 at North Korea’s Mount Geumgangsan.

The Korean Red Cross will contact the 500 people and the list will be trimmed down to 250 people based on their desire to join the reunion and their health. Half of the 500 people who made it to the first list are 90 years or older. The list of 250 people will also include the family members of 50 prisoners of war presumed to be still held in the North.

Then there will be more days of agonizing wait as the list of 250 people from the South and 200 from the North are exchanged on Sept. 19 so that each side can check whether the families they seek are still alive. The final list of 100 people will be exchanged on Oct. 8.

It always feels like a cruel lottery, the computerized drawing of names and then the seemingly eternal wait to see if one has been chosen for the once-in-a-lifetime chance to meet one’s family members after more than 60 years apart. The odds of making it to the final 100 is 662.9:1, to be exact.

Even then, the reunion scheduled for Oct. 20-26 hangs by a thread. Seoul had pushed for the reunion to take place before Oct. 10, the 70th anniversary of the founding of North Korea’s Workers’ Party of Korea, wary that Pyongyang was likely to test-fire long-range missiles to mark the occasion. Any test firing of missiles will be in violation of U.N. sanctions already in place against North Korea and could bring about further sanctions from the international community. In such an eventuality, North Korea is highly likely to unilaterally cancel the family reunion in protest.

The upcoming reunion is the first concrete outcome of the agreement reached between the two Koreas on Aug. 25. However, whether more reunions will follow remains murky, as North Korea negotiates in piecemeal fashion, using the reunions as leverage to get what it wants. In the meantime, the Park Geun-hye administration is demanding that a whole host of issues concerning separated families be resolved in one go.

Such a difference in approach was the main reason for the drawn-out Red Cross negotiations. North Korea wanted to focus only on the upcoming reunion while South Korea wanted to discuss a wide range of issues, including verification of whether the separated families were still alive, exchanges of letters, video reunions, visits to hometowns, and regular reunions.

The two sides agreed to take up the matter again at the next Red Cross talks but the difference will continue to plague any future Red Cross talks concerning the separated families. A way out of the impasse would be for top-level government officials from both Koreas to settle the differences once and for all. With more than 2,300 separated family members dying each year without seeing their loved ones across the border, time is running out to solve this humanitarian crisis.