Insert Value Not presented in the multi select list box choices access 2007

I have created a multi selected list box functionality like in the attachment which has a unbound control with possible choice of list items and also a text box were the selected choices can be inserted into the text box.

What it does? I am able to select one or all the choices that is present in the selection and click Insert and the choices are inserted into the text box.
I used the following code provided by How to retrieve the selected items in a multiple selection List Box as a comma-delimited string in Microsoft Access and it works perfectly

What it does not do? I want to also insert any free text in the text box ( other than the choices present in the unbound list box control ).

Please let me know how to do it. I am very new to VBA and programming.

Thanks for your help!

Thanks,
Rom

Attached Images

sample.png (3.9 KB)