Hello Anthony,
Unfortunately what you want can't be done. Apparently there is no method of showing a Report in a Form, although you could show a form in a report.
The only solution you have is to convert the report each time into a snapshot file using code similar to this:
DoCmd.OutputTo acReport, "RptToBeConverted", acFormatSNP, GetCurPath & RptName & ".SNP"
Then getting a snapshot viewer in access to pick that snapshot file up and view it.
Each time you change the combo, you then delete the original snapshot file, and then generate a new one with the same name to be picked up by your snapshot control in the access form.
It's the only way i could find that made it possible to do what you need to, there's no other way
btw, it's a relatively quick process though once you got it all to work.