Start with the knowledge that I am not a pianist. I always try to show things in the simplest possible way, and what I think is simple sometimes does not seem so to a pianist. Here's how I would handle this passage, as long as it ts not a facsimile transcription. I went back to Appendix C of the old De Garmo for inspiration, but did not find an exactly parallel illustration.
Since the pianist is clearly not to wait until the end of the duration of the eighth note to start the "grace notes," I think an in-accord starting with a "grace-rest" is necessary. I'd show the opening eighth note and two dot-5 eighth rests in the first side of the I-A. In the second side, I'd show the grace-rest, the opening bracket slur and all of the grace notes. I'd use the measure-division sign to end that line (the RH part will be similarly divided, with an I-A. In the next parallel, I'd simply end the bracket slur after the eighth note A. I don't think any concidence signs are necessary. I really don't see any reason to show the beams across the beats except in a facsimile transcription. I'll try to attach a Brasille2000 copy.
I'd very much like to hear a pianists's opinion.