Shouldn’t the Chofetz Chaim’s family be entitled to the copyright on the Mishna Brura or the Rambam’s family on Mishna Torah? Am I unaware of a time limitation halacha imposes on seforim’s copyright? I believe the Mishna Brura has been freely printed by anyone for at least the last 70 years, which was not all that many decades after the CC first published the last volume.
At what point can any printer print seforim without paying the author or his family? Are the seforim of the Chazon Ish, Steipler, Igros Moshe, etc. freely available to reprint by anyone? How does Hebrewbooks publish them?