How to add a fixed question after the last block (all blocks are assigned in random order)

I would suggest putting the last fixed question in its own block to start. What kind of content reference are you looking to make for the last question? Where you're randomizing the preceding blocks, more information may help determine the best way to accomplish your goal.

In my survey, I intend to ask respondents to evaluate 3 decision-making scenarios in 3 different domains. Scenarios will be displayed in random order. I intend to manipulate the decision-maker in each scenario and randomly assign respondents to one of the decision-makers: male or female. That is, there are 6 blocks in total, 2 blocks for each scenario. At the end of the survey, after respondents evaluate the third scenario (presented in random order), I want to add a fixed block that presented the other type of decision-maker (male or female), asking them to indicate which of the decision-maker they prefer. The content of this fixed block needs to relate to the last (third) scenario that respondents assess. The problem is that the scenarios randomly assigned, so each respondent receives a different scenario (domain and decision-maker). Thanks so much for your help!