Add to combobox list by entering new text in textbox

I have produced a userform that will show the correct use by date for any product we produce. The userform shows the date code in the correct format for the selected product so the operators can chack this against what is being printed on the carton or case.

Occasionally we pack a different product that is not in the list, I can easily add this but If i am not at the site it would be useful to have the ability for an operator to add a new product to the list.

I would like to add a userform with text box's to the workbook that can be accessed whan it is unlocked that will populate the combobox list and also add the shelf life 9,10 or 12 months (I guess the latter will require me rewriting a lot of code)

Can anyone help me with this?

Happy New Year


Thanks in advance

Please do not post attachments that alter the user's interface, nor attachments containing a load of 'security measures'