Customize Columns in Report Link?

I am embedding reports into some exact forms and it is recommended to accomplish this by creating report fields (like the ones that are auto-generated when you create a parent-child relationship between two tables). The reports are flagged as "Temporary Reports" by the system and display different settings pages from a normal "persistent" report. Attempting to save a custom report generates a new "persistent" report and therefor is not referenced by the report field. 

so, two approaches to answering this question: 

1. how do i customize the default fields that are displayed in the temporary reports generated by Report Link fields? Can this be done with URL encoding? by declaring fid="[desired field]" in the corresponding order of columns i desire seeing in the report? 

2. is it possible to embed a SPECIFIC "persistent report" i have already created through the report link field? rather than using the matching and target field interface in the settings page?

as usual, documentation is cursory at best on these concepts and could use advising on how to accomplishing this? i am not asking a paid service, rather community advice. Thank you in advance! 

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Alex Couts
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