Sharing a workbook by email

I work with a client who uses a worksheet for customer data. The client
inputs data then sends the entire workbook to me by email and I add
additional information (dates documents are sent to customers etc.) and send
it back to them. I obviously do not want to overwrirte the worksheet either
at my end or theirs as it is continually being updated. I am sure that there
is a solution but if someone could assist that would be great.

Thanks in advance

Just to clarify - I will overwrite the saved workbook with the updated file
each time it arrives by email and so will my client. It is just that the
workbook must continually show the original data plus any changes - I hope
that this makes sense

"SR7133" wrote:

I work with a client who uses a worksheet for customer data. The client
inputs data then sends the entire workbook to me by email and I add
additional information (dates documents are sent to customers etc.) and send
it back to them. I obviously do not want to overwrirte the worksheet either
at my end or theirs as it is continually being updated. I am sure that there
is a solution but if someone could assist that would be great.

Thanks in advance