1st point you are able get all the data by usign get tex?
if yes, get text activity outout will be in string format, here if you want give those values in input dialogues box each item should be separate with semicolon ;
Then only you can see drop down.
If you are not abel to get all dropdown values by using get text use get attribute by using items you are able see all drop down values and that will be in the form of list you need to convert that to string by semicolon separation(;)