Thank you very much for your answer.
I tried to follow the steps of the first way by using a random trigger.
I created an user defined variable with values from 1 and 2 ( I need 2 filter paths because there are 2 sets of questions).
First question is regarding where to place the trigger, I am not certain I placed it in the right place. I placed it before the 2 sets of questions start (in the question before). Do you think it is right?
Second question is regarding the two filters. I placed each filter right before each set of questions. What would the conditions and code be for the two filters in order for every 2 participants to get the same set of questions?
I don't know if I explained very precisely, so maybe it would be easier if you had a look over the project (ID is 444038).
Thank you very much in advance.