It all depends ... if it's a large modification I replace the whole thing.
I already know it's been modified so it doesn't matter if I remove the original code.
However, if it's a small modification (1-3 lines) I comment out the original code.
It helps when upgrading the forum.
You should do what is easier for you.
I have added my script into the CODE MODIFICATIONS forum.
https://vborg.vbsupport.ru/showthread.php?t=81524