Yes, this is very possible and should be practiced to keep your scripts modular. In my company it is our automation standard to do this.
1) create a new script.
2) remove "function main" and "end function"
3) Create your own functions
4) Add as many functions as you like.
5) In another script that has main you will include you script with the functions you built by using the "Include" command.
Now you can use all the functions you created in the "My_FunctionsScriptName"
Lookup "Include" in the QARun help for more info.
If your not part of the solution, there's good money to be made in prolonging the problem.