B3 joins and sends k3 (k3 > k2 || k3>k1+b1)
...
N. Bm sends kN (kN > k(N-1))
N+1. Auction ends
N+2. S withdraws kN and concludes
N+3. Bm concludes
N+4. Other Bs withdraw what they sent
Custom properties: ending condition, require acceptance flag, number of overbids
Scenario: