Your challenge, is to create a situation in which the Ottoman Empire has control of at least Warsaw and its present-day borders at the Oder River.
Any POD is fine, and having a Grand Duchy of Warsaw situation is fine here; however, it must be the Ottoman Empire, and not a Turkish leader in control of a future Pan-European superstate.
Any POD is fine, and having a Grand Duchy of Warsaw situation is fine here; however, it must be the Ottoman Empire, and not a Turkish leader in control of a future Pan-European superstate.