I have a case where field workers should collect data about multi-part features using Survey123. (Same feature consists of multiple polygons). I wonder if Survey123 can support multipart features and how to allow the geometry question to accept multiple parts this using Survey123 connect?
I doubt multipart will ever come. It went out of style almost as soon as it was invented. It can cause all kinds of analysis nightmares later.
I have simulated it one of two ways. One would be a repeat in the form. Put your geopoint question on there and they can make as many as they want. Parent can just be a point then show related to see them all. Make sure to test offline.
Second way I have done is to separate the geo and the form. We have users create all the polygons or lines they want in Field Maps then give them all the same FormID. One form has that FormID and they are related. I have links in the form to Field Maps to auto link the geo and I have links in Field Maps to the form that auto link that direction also. Bit more complicated but we really needed the flexibility to create the geo and forms in any order and sometimes months apart. Big advantage here is Field Maps can create polygons and lines while offline where 123 cannot without a downloaded tpk. Not sure if your teams will have signal so test this.
Then at the end of the season I combine all the geo and forms into one line per geo. Better for long term analysis.
Hope that helps