There should be a report link field on the left side of that relationship. Just put that on the form and specify that the records be listed directly on the form.
Then take that summary report and take off any filters which have to do with who the Parent is. Call it used on my Parent Table record B. Then in the form properties for the records in table B specify that Summary Report to use for the embedded report instead of a usual record picker or table report. QuickBase can embed any report, even a Gragp/Chart is a report. The report link essentially just adds in the filter so the children only display for the Parent record you are viewing.