I suggest everyone take a few minutes an dread the linked documents. Seems they were just filed on 8/5/08. There are many many letters from Lebowitz and Whiney Ellsworth castigating Siegel for bad stories, bad artwork, bad overseeing of talent, lack of cooperation, lack or seriousness, lack of gratitude(!) ... basically, if these were entered by DC, seemingly an effort o set teh stage for DC replacing them after years of generosity.
It also includes annual income totals by Siegel/Shuster for 1038 - 1947. Are you ready? $401K. But as you read the little details about their payments and shares in Superman's income, you have to wonder how much DC took in!
All in all, DC talks like a frustrated parent, putting up with these unprofessional kids. Certainly, there is some truth to this. But, if they were so bad, perhaps DC should have made good on their threats to replace them. But they apparently knew there was noone to take over until much later in the 40s. Anyway, its a big complicated enchilada. But fascinating.