Don't show records in main if subreport for the record shows no data

So here is a problem I have that I can't figure out.
I have a main report, one record pr line, place in a group footer.At the end of that same record line is a subreport. Is there any way to not show records in Main if the Sub does not contain Record? If Main returns 20 records, but 10 of them don't return anything in the Sub, I don't want those records included. I can't for the life of me see any way to do this. Any hints and ideas?

You should give more details about the tables from where the data is coming
Describe the tables for the main report and the tables for the subreport
Is there a relationship among them?