I am using Vi Editor for editing a file.
I am doing a Remote login into another machine and making changes in the file as we both had to edit the same file.Some Swap files are created as more than one person is editing the same file. When I save the file it generally gets saved. But after sometime, if I open the file again, the changes I made are not reflected. The person who edited the same file , her changes are reflected.
This file is in her system.
I am so confused. All my work is lost. IS there any secure procedure that two people can edit the same file?

Is VIM Suitable editor for doing so?

Looking forward for the reply.

The answer you are looking for is CVS (or subversion). There are no editors (I could possibly be mistaken.. but I've never seen one) that automatically handle versioning when two people are editing a file simultaneously. Vim for instance, will complain if you try and open a file that somebody has already opened in vim (unfortunately it doesn't complain if somebody has it open in another editor).

CVS allows each person to checkout there own copy, edit it, and then commit it back to the repository. It will automatically merge changes when it can, and ask you to manually merge changes when it gets confused. CVS (again.. or subversion) will also allow you to go back and check the differences between different versions of the file and revert back to old versions. In short, using a versioning system insures not only you never lose your new work but you'll always be able to go back and check out your old revisions as well.