But even in Poland public executions were relatively rare after end of the war. Hanging of Arthur Greiser in front of large crowd (50k) in Poznań was propably the last.
Ladislaus I/V (1377-1422) King of Naples 1386, King of Hungary 1404 [1] m. a) Constanza Chiaraminte (annuled), b) Mary of Cyprus (1381-1433)
1b) Charles III (1404-1453) King of Hungary 1422, m. Margaret of Austria (1416-1486)
2b) Andrew I (1407-1461) King of Naples 1422, m. Margaret of Savoy...
In Polish not only names, but even nouns can't end with -u (except for some fresh borrowings, mostly from Japanese). Form Jam OTOH would be confusing ( "Jam jest" could mean both "James is" or "I am")
Sigismund was afraid, that Władysław (who was his only adult son at the time) would be murdered by his Russian subjects, like False Dmitri, maybe (just maybe) he'd be more willing to accept the risk, if he had spare adult son.
While Prussia could let Russia take Posen if compensated elsewhere, UK and Austria would strongly oppose, as Russia with Posen comes to close to German heartland.
Elizabeth of Austria and Casimir Jagiellon have less kids, but Jagiellons are more successful in the long run (as Jagiellon brothers would not fight over Hungary in 1490 like IOTL and Poland and Lithuania would not be split in 1492)
Casimir III [1] (1427-1492) Grand Duke of Lithuania, King of...
Germans could not know what he'd do if they made no deal with him and he may approach France & UK if hostile Germany expands at his doorsteps. Germans would not be willing to risk any possibility of 2 front war after ww1 experience, so would just make deal with Stalin and give him eastern...
He at least knew about German invasion in advance and was given free hand in his direct neighbourhood. If ostentatiously anti-communist Germany pushes their sphere of influence further east, he'd have reason to be worried. Germans must consider this and ensure, that Stalin would remain at least...
They still had priorities. Uruguayan or Chilean SSR could wait for their turn, lands near Soviet border, populated mainly by dominant nations of two Soviet Republics, are different story.
Not only this. USSR wanted revenge after Polish-Soviets war and regarded lands east of Curzon line as western Belarus/Ukraine. Even before 1939 they divided Eastern Borderland of Poland into Belarusian and Ukrainian part ( Belarusian and Ukrainian communist agitators have their districts)...