In Data | validation | list

how can I define the list to contain both text constants and result of
function (in my case OFFSET)?

I tried constant1;constant2;=OFFSET(.....) in the dialog box, but it won't
work...

I use dependent data validation created from sorted list with two columns,
but two specific fixed values are always valid no matter what the first
selection is. I'd prefer not to enter them "100's" of times in the sorted
list.....