Don't sim multiple predictions in 1 frame -i could hear my gran'ma screaming-
You want to simulate them from the rollback frame (the one that failed) to the current frame. Then grab local inputs again and predict from the current frame on. Look at the diagram u posted of ggpo, it shows you that failure between frame 3 and frame 4, right?, but u rollback to frame 1 and u sim to frame 4 ( the reason u roll back to frame 1 is because remote inputs have arrived and are informing u that your prediction is wrong and these remote inputs are still on frame 1. So u rollback to frame 1 (or whatever that failed frame will be in your case))
So you rollback to the frame of which the remote inputs (when they have arrived) indicate that those players are at! And then you simulate to the current frame 4 (which means you will be repredicting in some of these frames) and then finally you can gather local input data again from frame 5 and predict (and so on and the cycle goes on etc…)
That's kind of what ggpo does when it rolls back (in a nutshell). Also, that's why ggpo gathers all inputs from all players BEFORE the next frame is executed, this gives the best predictions (it's not about sharing network performance or load), it's about giving your system the best chance of predicting correctly (but yes unfortunately when prediction fails then u rollback as mentioned)
I hope this makes more sense now, I predict that u understand it better now ?
Have fun ?