Hello @Mario_Kiessling
This is very easy to do correctly - please make and share a dummy doc in which we can show you the solution.
There is more than one way to do this, but the formulas could look something like:
TableName.filter(currentvalue.Stage=@requested).Holidays.sum()
Or even simpler: make a view of your table, group on Stage and show the sum() of Holidays.
I don’t like SumIf, but I guess that could work too.
Greetings, Joost