I’m probably not the best person to comment on this aspect.
While I will have to decide exactly how to represent these kinds of more complex relationships, I haven’t gotten there yet. I look at it this way: if trying to build a highly structured model around a fully representative embedded schemas model is complex, doesn’t feel sufficiently natural, and doesn’t come with sufficient benefits to merit the trouble… I’ll likely not try to create a single embedded schema which faithfully models the entire form and be content with managing simpler collections of embedded schema structs which, on their own, represent discrete, independent form elements.
My goal with embedded schemas is simply validating input by “users” (meaning any external input), coming through a web interface or via an external API, so any answer that accomplishes that will be sufficient with the only question being which approach is optimal. Ecto facilitates a number of approaches in this regard. Again, figuring out the optimal approach, including how embedded schema associations work and their pros/cons, is a “future me” problem.