Loop and Merge - utilising display logic answers

HI all
I have a survey where I have 2 hierarchies of questions - the user has to select
1st level Category - a category/s (multi choice / multi answers)
Then 2nd level Activity - activity/'s that relate to the category selected at 1st level (multi choice / multi answers - utilising Display Logic based on the answer at 1st level)
After that, I have a string of questions which need to be asked for each of the 2nd level activity/'s selected. I have set up a new block with Loop and Merge but can't seem to get the 2nd level activity questions to appear as an option in the "Loop and Merge/Loop based off of a question" section. I can see the 1st Level Category available to be selected.
I imagine this will be due to the 2nd level questions using display logic but am wondering if this is correct and if there is a way around it please. I don't want to create a massive amount of hard coded questions if I can avoid it.
Thanks for any help 😊