Disintegration of the material while doing GRN

We receive the material in the Container Boxes and charged for the whole box.

Each Box in turn contains 2000 different raw materials in predecided quantity.

How can we establlish a scenarion in which we will do the GRN of the whole Box but the inventory of the 2000 raw materials in the box will get updated as per the predecided quantity.

E.g Each box conatins 3 raw materials (RM1, RM2 and RM3) in quantities as follows

RM1 -- 20 Nos

RM2 -- 5 Nos

RM3 -- 1 EA

Now when I do the GRN for the Box my inventory for the Box goes up by 1

Material Stock

Box 1 Ea

RM1 0 Nos

RM2 0 Nos

RM3 0 Ea

Now what to do to convert this one box into different raw materials like following

Material Stock

Box 0 Ea

RM1 20 Nos

RM2 5 Nos

RM3 1 Ea

regards,

Akshay