filter data from a grouped table

hi everyone

i need to filter data by parameter with a relationship.

my problem is:

the data is a table of monthly forecast, but i need to brake it to a weekly forecast

and to connect it to a weekly line chart (by a relationship with the month column,then to apple the weekly tquant by the month)

and divide the total of the month quant to a 4.3 and steel keep the option to filter the data by a specific parameter.

the problem is that when i group by the table - i am not able to create relationship between the parameter column and the parameter table. i put here some data: