Paginated Report - Parent/Child Datasets

I have three datasets: ReferralCase table ("parent"), SurveyResponse table ("child"), and ReferralsInDateRange (taken from a slicer in Desktop).  They are all created in DAX from Desktop, but then I modifed them for the multi-select.

The parameters I have set are a start date and and end date, from which the Referrals parameter populates based on the referrals in range.  Then the user can multi-select which referrals to select.

I have the initial header section working fine with the multi-select, but I don't know how to get the detail information from the SurveyResponses to populate right after each respective group (referral).  The tutorials I have found online all show data only from a single dataset.  I would like to know how to utilize the key value (Referral_ID) and pass the respective parameter value to the detail table.   Then each referral selected would show the referral/case detail followed by the zero, 1 or more responses on one page, then the next referral with its responses, etc.

Do I use a list or a subreport?  How do I tell the list/subreport which Referral's survey responses to pull?  Do you have a step-by-step resource to walk me through the steps?  I have attached my RDL.  I am really stumped.  Thank you so very much!

https://mwtn-my.sharepoint.com/:u:/g/personal/dkernen_mwtn_org/ETeHifJn0idOmwsIAl1ShbMBzw6N3qlbcRXQqesxNc23Eg?e=l8KaUk 

@multi-select, @paginatedreport, @parentchild