I would:
1) Move on from McSorley once he is no longer needed to toss balls around in practice, which may be like tomorrow. If you feel bad about it, ring him up about an umbrella policy.
2) See if anybody'll give you something for Zappe. He's a perfectly serviceable backup with little to no discernible upside and thus no prospect ever of starting, so you might get a minimal something-or-other for him. In all likelihood, though, you won't be offered much, in which case you waive him and, if he passes through, put him on your practice quad as a backup to the backup. If somebody does take him off the wire, find some serviceable old utility qb and put him on the practice squad as your backup's backup. They're out there. I'd rather have Zappe, who is familiar with the system, than the crusty old vet, but there is tight limit on what resources I'd be willing to sacrifice to accomplish that.
3) Make Cunningham the backup for two reasons: First, he really does have some very intriguing upside. He's athletic, he's tough, he seems like a worker, his teammates seem to respect him, and he's not as dismal a passer as the pontificating gossip would have it (though no one would say, as Bill often does of all sorts of qb's, "He can make all the throws." He can't, yet.) It's reasonable to think he can develop in an acceptable time frame into a passable backup for this season. In the meantime, his versatility (which FAR surpasses Zappe's, certainly) further enhances his value. The second point is that particularly given that we are far earlier in the rebuild than we sometimes like to think, we need any number of players on the roster with upside, players who it seems might really develop. We seem to have adopted this approach to an extent in our draft philosophy, but that doesn't mean a thing if you do not have the Moxie to keep those players so that they can develop. If we were putting the finishing touches on a really competitive team to ensure it's success, that would be one thing: the reliably mediocre Zappe would then be the choice, and you would just take a flyer at trying to get Cunningham onto your practice squad. But that's not where we are, we are a mediocre team with serious shortcomings in a number of areas, shortcomings very unlikely to get addressed this year, frankly. We are likely the weakest team in our division. Such teams cannot afford to set aside players - at whatever position - with the sort of upside anyone with eyes can see in Malik Cunningham, certainly not so that we can hold on to a fine but limited fella like Zappe. The fever has broken and the bell has tolled on Zappe Hour. So it goes.