Ability to include multiple subtotals in Sale Order

Is it possible to have sub totals in Sale Orders?

For Example -

Option 1

*SKU 1

*SKU 2

*SKU 3
 

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*Subtotal of SKU 1 + SKU 2 + SKU 3

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Option 2

*SKU 4

*SKU 5

*SKU 6

*SKU 7

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*Subtotal of SKU 4 + SKU 5 + SKU 6 + SKU 7

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Document Subtotal would then be SKU 1 + SKU 2 + SKU 3 + SKU 4 + SKU 5 + SKU 6 + SKU 7