How can a file be in multiple folders without shortcut form?

i want different paths all lead to one file , but not the shortcut way.
for example , file "a" is in folder "A" while it's also in "B" .

please tell me how to make it .

and i also wanna know if i delete "a" in "A" , would the file still exit ( there is a "a" in "B" ) ?
if i chang the file's name "a" into "aa" in "A" , would the name of which is in "B" be changed?

thanks for you help !