forecast on "family" or subassembly

Dear all

i have forecast from sales on family of product, not on individual end items. sales team is not able to forecast on end items and it will not be relevant to do so.

of course our sales order are on end items.

i would need the mrp to take into account the forecast on family and to check the sales order of the sales items belonging to this family.

is there a way to handle this in Nav ? or should we do a specific development ?

thanks

Fabrice