The title is quite generic, but the situation is the following: I have a posting market and after each round the buyer can send a private offer the seller(s) they interacted with. The offer will appear on the market screen of the respective seller in the following round. What I am struggling is how to get the offer to the right seller? I have a unique participant id stored, so I know who the sellers were when I ask the buyer to make the private offer. But how can I retrieve that information in the next round and show it to the right seller? Hope this is enough information, the code base is so large that I can't post meaningful real examples.

I see two options: 

The more straightforward way probably is using participant variables to get the info to the next round: https://otree.readthedocs.io/en/latest/rounds.html#passing-data-between-rounds-or-apps

The second option could be working smoother, but it probably is a bit hard to get right; use live pages (there even is an auction example on the documentation): https://otree.readthedocs.io/en/latest/live.html.

This way, you don't need rounds and WaitPages and such things.

Thank you!