Pivot table and calculated items based on condition

[liulilli]

Hello,
I have a problem with a pivot table for which I've been struggling for a while, without being able to reach a solution. I'll try to explain myself as best as I can.
I have a data source composed like this:

PRODUCTS	Month	Sales
A	01/01/2023	10
A	01/01/2023	10
B	01/01/2023	20
C	01/01/2023	30
C	01/01/2023	10
A	02/02/2023	10
B	02/02/2023	20
C	02/02/2023	50
C	03/03/2023	10
B	03/03/2023	20
A	03/03/2023	40

From this data source I create a pivot like this, summarizing the sales:

	01/01/2023	02/02/2023	03/03/2023
B	20	20	20
C	40	50	10
D (calculated item)	(A * 0,5) = 10	(A * 0,5) = 5	(A * 0,5) = 20
E (calculated item)	(A * 0,5) = 10	(A * 0,5) = 5	(A * 0,5) = 20

I need the pivot table to split the sales of product A in different percentages based on the month:

	01/01/2023	02/02/2023	03/03/2023
B	20	20	20
C	40	50	10
D	(A * 0,5) = 10	(A * 0,7) = 7	(A * 0,3) = 12
E	(A * 0,5) = 10	(A * 0,3) = 3	(A * 0,7) = 28

I have freedom to create additional helper columns on the data source and on the pivot table, but I cannot create macros unfortunately.
If someone could help me with this, I would be immensely grateful

Thank you in advance and have a great day!