Hi Andrew,
Firstly, thank you for taking the time to explain the concepts and reasoning behind your suggestions - it is much appreciated and builds on the little Excel VBA knowledge that I have.
I would like to be able to say that this was an assignment...but in this case it most definitely isn't. This is a 'proof of concept' for something at work and to 'put someone in their place' who swears it can't be done using Excel.
Yes - the labels are mutually exclusive. Nine times out of ten, there will always be one of the labels used. That tenth time, there won't be a need for a label but there will be a need for Marking 1 to be used and to be situated where the 'current' four 'label 1' are showing. Otherwise Marking 1 will sit underneath whatever the selected 'Label' is and as seen in the bottom part of the ToFrom worksheet.
Hopefully I have been able to complete all of the preparatory steps correctly. Guess the proof of the pudding will be in the attached updated workbook.