force using function definition contained in script instead of external file

Sometimes I write some functions in Rscript (myscript.R) that copied to an external file (just_functions.R). Rstudio indexes all project files by default, so when I press F2 is opening the external functions file "just_functions.R"

It happened that i've modified the original function in "myscript.R" but Rstudio keeps executing functions contained in "just_functions.R"

I want to force execution of function if exists in the same script as we are executing, otherwise search outside.

I've tried deleting external functions file but this breaks myscript.R execution giving an error.

How can I force this behaviour?