What tools or processes have you implemented to estimate rehab costs more accurately and avoid scope creep in BRRRR projects?

Obviously if you’ve done this before you likely have a method you prefer for dealing with these types of things.

I'm not 100% sure about each one's different benefits and cons, but which method would you recommend to use if you were in my position?

If the same people are involved, it doesn't matter.

If you have it in emails etc. you could have a position - but as another poster mentioned, giving up $100 a month in rent to only paint two rooms is very very generous so I can see how they thought there would be more rooms involved.

By the time I got to that point the cost and time involvement was so high I decided it was a distraction to what was already working.  

After about a month of no response on FF I switched my method to LTR.

Don't get involved at all in domestic violence - who stays, who goes, taking sides, etc.

@Abigail King I mean, I wouldn't classify it as "creative financing" as much but my favorite strategy has been the BRRRR Method for many years.  

@Tom EvansCongrats on the potential STR in AZ.As for a shared well agreement, they can be tricky (even when it does not involve STR usage).