How can I set up RNG Conflict with a multi day event
This is my interpretation of your multi day seminars:



I think for your first scenario where there is no conflicting sessions, there is no need to enable RNG Conflict.

For the second scenario where you have multiple (3-5) sessions potentially running at the same time. You should have some field on the event nodes that uniquely identify each. You could do this by:


Adding a integer field representing the timeslot number (timeslot 1, 2, 3 etc). Or,
Add a date field on each event with the start datetime for each session. Then set RNG Conflict to use one of these options.


You may also want to add a field representing the overarching seminar. Resulting in something along the lines of:




Your site only needs a single event type (a node type, etc), and a single registration type no matter how many seminars you have. If you are customising your registration form then you may want to add more registration types, but this would be unusual.