How to randomize questions before and after a block without repetition

Hello everyone, I need to randomize 12 questions such that 6 of them appear before a block of text (in random order) and 6 of them appear after that block of text without displaying any questions twice (thus, no question presented before the text block would be shown afterward). I understand how to randomize questions within a block, or randomly display only 6 of them. So, what I need to know is how do I display 6 before and 6 after a text block? And how do I ensure that no questions are repeated? Thanks! So far the set up is: Question block: Q1 Q2 Q3 Q4 Randomly display 6 of 12 questions in random order before text block Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 TEXT BLOCK