Let say I have checked out a file "file.c" from main line. In that file suppose there is only one function say "add()".
I am going to implement one more function in that file say "subtract()" for that I checked out the file and I've implemented "subtract()" function.
Now, suppose in the same file another person implemented a new function say "multiply()" and he check in that file to main line and the new version is created for that file in the main line.
My question is: the file which I've checked out in my activity branch is having two function one is "add()" which was already there and one function is "subtract()" which is implemented by me.
I want the third function i.e. "multiply()" in my file without affecting my changes in my activity branch. I don't want to do check in to the main line, just I want all three functions in my checked out file.
So my file will contain three functions add(), subtract(), and multiply().
How can I do that (without a checking triggering the mergetool)?