Hi Experts,
As per one of our business requirements, we have created two Custom entities under SAP MDG-MM data model. YBUPA01 for which the leading entity is MATERIAL, and another custom entity (YYPARTNER) which is a child of the custom entity YBUPA01,and both of these entities are list UIBB sections in the UI.
I have followed the below SAP How-to document for this requirement:
https://www.sap.com/documents/2015/07/aa24484d-5b7c-0010-82c7-eda71af511fa.html
Please find the below screen shots below for visualization of the Data model and the MDG UI.


As per the Data model design, Business partners section represents the entity YBUPA01, and BP systems represents the entity YYPARTNER.
As per the SAP How-to document, the Feeder class that I used for both List UIBB sections is CL_MDG_BS_MAT_FEEDER_LIST
The source config for the second section i.e BP system is ZMDG_YBUPA01 and Connector class is /PLMU/CL_FRW_W_CONN_DEFAULT, and refer the below screen shot for wiring, and also the the selection mode property s enabled for the parent UIBB.


Issue: on Change of lead selection in the Parent section(Business Partners), the corresponding entries were not getting pulled in the child entity section(BP systems). By default, the child entity section loads all the entries from the staging table of the entity YYPARTNER. The lead selection change in the parent UIBB has no impact on the child entity section.
Please help me to fix the issue, the child entity should only pull the records relevant to the record selected in the parent section.
Thanks,
Xavier