Do you have access to a compiler of some sort? What about writing a new .exe that shells each .exe in turn? Something like;
shell a.exe
shell b.exe

That's how you could run each in turn, but I don't know how you would get the results. Alternatively, you could put an input box in to replace a.exe and then just shell b.exe, i.e.
if input("Your password here") = "secret"
then shell b.exe
else exit
end if.