How did I overwrite a file to in "tar" file.

For example I have file "backup.tar" in my home directory, which contains two file "x.sh" and "y.sh"

I made some changes to one of the file "x.sh" and want to update the "backup.tar"

I use tar -uvf, but this appends at the end of the tar file, but what I want is replace the file.

The only way, I know of right now is, delete the file by issuing the following command

tar --delete --file=backup.tar x.sh

and then adding the file again using

tar -uvf backup.tar x.sh

Is there a better way of doing this, on a single command.

Thanks in Advance