Problem: If "Sam broke both his ankles and he's walking with crutches. But a month or so from now they should be unnecessary.", is "The ankles should be unnecessary." correct?

Answer: no

Problem: If "Lionel is holding captive a scientist, Dr. Vardi, who has invented a device that turns animals invisible; Lionel plans to use it on Geoffrey and send him to steal nuclear material from an army vault.", is "Lionel plans to use it on Geoffrey and send Geoffrey to steal nuclear material from an army vault." correct?

Answer: yes

Problem: If "Since Chester was dependent on Uncle Vernon, he couldn't very well marry without his approval", is "Uncle Vernon couldn't very well marry without his approval" correct?

Answer:
no