I'm not entirely sure what you want but:
maybe you want to set the users default permission so that only that user can alter the file. see:
maybe you want to set the higher directory to sticky:
chmod +t [directory]
from the same file:
The "sticky bit" also has a different meaning when applied to directories than when applied to files. If the sticky bit is set on a directory, then a user may only delete files that the he owns or for which he has explicit write permission granted, even when he has write access to the directory. This is designed for directories like /tmp, which are world-writable, but where it may not be desirable to allow any user to delete files at will. The sticky bit is seen as a t in a long directory listing.