Hello - in the following sentence "John and Michael, each in his own way, changed the outline of the design" - is it correct to write "each in his own way" or is it "each in their way"? And what happens if the sentence starts with "Each in his/their own way"?
"Each in his own way" is fine.
Nothing happens if you start the sentence with the phrase:
"Each in his own way, John and Michael changed the outline of the design"