Measure different grain

Hi everyone,

I have been working on Power BI for a few months and now reached a point where I really need help. So I hope you can and I already thank you for it.

Here is the situation :

My hierarchy is as follow :

Raw budget

Detailed budget

Time tally table

First I want to calculate the remaining time

I tried this :

Measure = VAR Timeleft = SUM ( DetailedBudget [Time] ) - SUM ( Timetally [time] ) 
RETURN
IF ( Timeleft > 0 ; Timeleft )

And its working when shown again the Task dimension but its wrong when I show it for a project (The total time spent is greater than the budget so this measure will show 0 time left when used with project dimension.

I kind of made it work with calculated columns but then the time left to do is not updating depending on the date slicer.

Then, I need to check for a given Phase, if there is no Detailed time budget then use the Raw Budget.

the result would be something like that:

Thank you very much for reading through this and please ask me if you need extra details. I'm so overwhelmed by this that just explaining it is difficult.

Cheers!