Defaulting and Mass Update of Sub-Inventory in Sales Order

We have a requirement around Defaulting and Mass Update of Sub-Inventory in sales order. These are the must have requirements:

- Need to make Sub-Inventory Mandatory in Sales Order

- Able to  enter sub-inventory at sales order header level and the same need to be cascaded at sales order line level

- Ability to override the Sub-Inventory at line level

- Ability to have Sub-Inventory in mass change form

Any pointer in this regard will be helpful.

Regards,

MK