In my opinion, the reference that LQuinn posted is interesting but not directly relevant to the question asked.

There is a lot of work to make this happen and to me the requested useability doesn't match the amount of effort to realise this workflow.

My questions are:
Is this a real task or a vba learning exercise?
Is there only ever 4 customers?
Is there only ever 3 replaceable items?
After an item has been replaced, will you want to find that same location again (linked to the same row) to do another pass?

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Andrew Lockton
Chrysalis Design, Melbourne Australia