Updating & closing items in Sales Order

Hi, we're using 2007.

When I need to update as well as to close multiple item lines in a Sales Order, I'll need to do this:

1. Call GetByKey()
2. Call SetCurrentLine()  // point to item to be updated
3. set Quantity = 10  // for example updating quantity
4. Call Update()
5. Call GetByKey()  // to reload the document
6. Call SetCurrentLine()  // point to item to be closed
7. set LineStatus = bost_Close
8. Call Update()

So I just want to confirm if this is the correct way to do it, ie. calling GetByKey doing Update() 2 times?

Please advise.

Thanks.