A dynamical dropdown list which autoupdates and autosorts alphabetically

I have an excel Sheet1, with cell B6 containing data validation. The range is in Sheet2, column A from Cells A2-A100.
Here is my question, I wish to enter a value in cell B6, which contains the data validation list options as they are in Sheet2.
Is there a way I can enter a new value in cell B6 which is not in the dropdown list of Sheet 2? So that I do not get an error message and the dropdown list in Sheet2 will get auto updated by that new value and will be automatically sorted alphabetically.
I hope I am clear with my query.
Thanks in advance.

Thanks for the help. I solved my problem.
regards