Macro - Copy aggregate qty to detail qty

Hi all,

I want to copy a qty at an aggregate level down to the detail level in another KF. e.g  the agg amount 1000 in KF1 below - I want to copy to the detail of KF2:

KF1                    1000

          Det1          800

          Det2          200

KF2                    2000

          Det1         1000

          Det2         1000

Any ideas?

Thanks!