Overwrite existing scheduler and script enteries

RouterOS Scripting
1

How do I achieve overwriting existing files in scheduler and scripts with updated versions!

2

How do i workaround “failure: item with this name already exists”

And there must be a better way than having this at the start of the script;

/system scheduler remove numbers=0
/system scheduler remove numbers=1
/system scheduler remove numbers=2
/system scheduler remove numbers=3
/system scheduler remove numbers=4

/system script remove numbers=0
/system script remove numbers=1
/system script remove numbers=2
/system script remove numbers=3
/system script remove numbers=4

3

To add something, use “add”. To change something, use “set”.

4

I tried “set” but it stops when it reaches “owner=…”