I believe that if you want to reuse previous answers to dialogs you can create a pick list on the fly; however, this does not work for me because I have repeating dialogs where each "tier" allows the user to input 1, 2 or 3 names (such as sole trustees or co-trustees), and pick lists only allow one choice per dialog.
So what I do is, I use computation variables to create a multiple choice variable on the fly containing all the names the user may want to select for fiduciaries. First I put in a computation that clears the multiple choice variable at the beginning of assembly, then after collecting the names I populate the multiple choice variable by doing computations such as:
REPEAT NamesOfChildren
ADD NameOfChild TO MasterListOfNames-mc
END REPEAT
Then, whenever I want to allow the user to select, I insert the multiple choice variable at the end of the dialog as a dropdown list, and instruct the user to select the name, cut and paste it into the appropriate dialog box. (For each such dialog, you must select the dialog option "Use only with Ask instruction.")
Explanation
The suggestion I would like to add is the following. If you are going to go to the trouble of building the computation structure for a generic CLEAR + ADD dynamic Mulitple Choice variable builder, why not have it create the specific MC VARs that you need. In the situation below, have the ADD statements inside the REPEATs ADD the entry of a child's name to each of the 5 MC VARs that are really needed. The work to create the general MC VAR list is the hard part. Making the computation load 5 specific MC VARs from which you can have a multi-select response that gives you a discreet output for your answers is quite powerful for not much extra effort. It is also more durable and less fragile than doing the cut and paste with that operation's own complexities.