Please watch this from The Master himself to know exactly what dire problems you'll be facing when building one-table models... and DO NOT DO IT under any circumstances. Always go for the star schema if you want to produce correct numbers or at least minimize the probability of the problems manifesting themselves in your model. Sadly, the auto-exist problem can't be avoided fully in Power BI 😞 and you have to be prepared that once in a while your formulas WILL provide a wrong number. That's UNAVOIDABLE. Sorry.