Editing the Data Update - best practice

Hi, the Data Update is amazing, however there are a few tweaks I would like to make based on my own preferences (e.g. adjusting some CA/PA, manager tactics, finances). 

What is the best practice to apply here?

Editing one the Data Update files? But which one, “Players and Staff” or “Changes”?

Or is it better to make a new file (I guess based on the old 21.4 official db)? 

How are potential conflicts managed by the game? For example, if I edit something that is already edited in another file, which version is loaded by the game once I start a new game?

Thank you

Create new files to run alongside I give some tips in the FAQs on this 

The only issue may be editing finances as there  may be a file on this in the data update, if so I would edit that rather than have your own one as well just to rule out any potential clashes