If a person accidentally forgets to daven during the day, in most cases he has the opportunity to "make up" that davening by saying shmoneh esrei twice in the next davening. This is called tashlumin.
Lechatchila, a person should daven with a minyan. Is this the case for tashlumin as well (ignoring the fact that presumably the minyan didn't get up and leave immediately after his first shmoneh esrei)? What if he could never have managed to find a minyan for the tefila that he missed, but happened to have one for his "make up"? Is it as if he davened his missed tefila with a minyan, even though he could not possibly have done that?