Address not chamging for Kit Items

Hi,

We have Two Scenarios:

-- Enter a Sales Order -- Enter Lines with Kit Item -- Change the Bill to Address -- Save the Record -- Bill to Address got updated for Component items too..

-- Enter a Sales Order -- Enter Lines with Kit Item --Save the Record -- Bill to address is defaulted from Header -- Change the Bill to Address -- Save the Record -- Bill to Address is not getting updated for components

Can anyone help me in this to find out the actual reason behind the difference.

Thanks in Advance.