Hi SKA,
Yes, u can split order quantity in same GR screen to post it to diff.storage location.
In GR screen , if u see in-between Header data & details data , a icon like 'X' i.e.distribute quantity.
Click on it, in next pop-up, give distribution details(90+10), enter.& see the result on the GR screen.
Maintain storage location accordingly.
Pls. revert .
Regards,
Milind