Building an Inverse Tree

Hi all,

I have got a problem in building a logic for an inverse tree .


Ihave got 4 tabs namely current yr target,half yr target,quarterly target,monthly target,weekly target.
In current yr target tab there is a textbx for entering the target.Once target is entered
ex 1000
1)500-first half yr trgt and 500-second half yr target.(Half yearly target)
2)250-First quarter trgt,250-second quarter trgt,250-Third quarter trgt,250-Fourth quarter trgt(Quarterly target).
like wise each quarter will have 3 months so target gets propationately divded.

This some thing like inverse tree with yearly target at root
and weekly target as leaves.

Can any one help me with the logic

Thanks
Murali