That works for moves like Falco's Up Smash, but what about moves that realistically, they're going to hit multiple times and you can't hit each individual hits separately like Zelda's Up Smash?
Oh, and for aerials, you'll have to add (technically subtract) landing lag, right? So, Falco's Dair, using the shield stun calculator, would give him a -40 frame advantage, but he also has 23 frames of landing lag. That would make it -63. But for auto-canceling aerials like his Bair, if you go with the calculator and input the total frames, technically, the total frames are something like 4, his hard landing frames, instead of 37. Normally, it'd be -28 with 15 frames of landing lag making it -43. Inputting that would make it +5 on shield with shield dropping, +7 frames to the frame advantage, making it +12.
Yes, my brain hurts.
So for moves that hit multiple times, the same thing applies. Each hit of the move connects with a shield, and does a certain number of shieldstun frames. You could think of it as using multiple moves, if that helps. Zelda's smashes aren't very good for examples since they have 0 frames of shieldstun on the first few hits, so I'll use an imaginary move for my example.
This move has 34 total frames, and hits on frames 7, 12, and 23, with each hit doing 7, 9, and 14 damage, respectively. (that sounds broken)
Move Frames 1-6
Move Frame 7: Hit 1 (2 frames of shieldstun)
Shieldstun frame 1 / Move Frame 8
Shieldstun frame 2 / Move Frame 9
Move Frame 10: Defender Actionable
Move Frame 11
Move Frame 12: Hit 2 (3 frames of shieldstun)
Shieldstun frame 1 / Move Frame 13
Shieldstun frame 2 / Move Frame 14
Shieldstun frame 3 / Move Frame 15
Move Frame 16: Defender Actionable
Move Frame 17-22
Move Frame 23: Hit 3 (5 frames of shieldstun)
Shieldstun frame 1 / Move Frame 24
Shieldstun frame 2 / Move Frame 25
Shieldstun frame 3 / Move Frame 26
Shieldstun frame 4 / Move Frame 27
Shieldstun frame 5 / Move Frame 28
Move Frame 29: Defender Actionable
Move Frame 30-34
Move Frame 35: Attacker Actionable
For landing with aerials, just add the landing lag of the move (or the hard landing lag for autocancels) to the frame that you land on and use that as total frames. So if you land on frame 28 of Falco's dair, use 51 as the total frames instead.