Sidney Sheldon: "Samuel Roffe, the founder of pharmaceutical company Roffe & Sons in Bloodline, didn't like the idea of his company ever being owned by strangers, so he made bylaws to make sure nobody other than people born or married into his family could own shares, join the Board of Directors or become CEO and that his heirs could never sell their shares."
Ambiguous cases, may or not be misuse (9)
Series.Amen: "An elderly parishioner dies and leaves her successful restaurant to the church. They can use some of the profits for church projects, if they keep the restaurant open. Hilarity Ensues."
Arabian Nights: "The law that the Sultan has to remarry or give up the throne."
Dance till Tomorrow: "Suekichi needs to 1: Finish college, 2: Get Married, and 3: Establish a career."
Doorways in the Sand: "Fred remains a student because his uncle died and left a substantial fund to provide for his education; when he graduates, the remainder of the fund will be donated to the Irish Republican Army."
Rename and broaden could solve the problem. The current trope description references a specific plot (will with a catch and the lengths a character has to go to as to satisfy these conditions), while the examples tend to go for the plot device (will with a catch). If we redefine this as the plot device, the old examples stay correct.
Legacy With A Catch is the term Ethan Mordden used in his survey of 1920s musicals, where it was a fairly common premise (though the best-known theatrical example from that era is the non-musical The Cat and the Canary).
Merriam-Webster gave two definitions. Maybe I read too much fantasynote (which would be ironic since I don't read in the first place) but I always hear "legacy" used in MW's definition number two: The metaphorical sense rather than legal will. Heck, three of MW's four examples demonstrate that definition as well.