In my worksheet, I turned on "Protect Sheet" so that users can't view or
modify locked cells.

But since I still wanted them to be able to modify unlocked cells any way
they wanted, I selected all the options in the list of "Allow all users of
this worksheet to" features in the "Protect Sheet" dialogue box (except for
"select locked cells" obviously).

However, the users can't seem to merge unlocked cells. Is there a way of
including this functionality in the allowed actions?