Stock Cover Months

Hi, yes you are right, there are a few lapses, and generally the DAX code that I've written does not give me the outcome I want. I've created an excel with the same format and expected resutls by each branch and model at the different levels (https://we.tl/t-QYLx2WyuNU). As for the date column, only the sales plan has a date/timeline, in which I plan to use month number to reference the months within a year for ease of calculating the month cover.