If you get error CPD7812 Subfile control record overlaps subfile record when compiling DSPF.
One of the reason can be that subfile control record can have data displayed either above the subfile or below the subfile but not both.
If you want to show data both above and below the subfile, common way is for the control record to have all the heading information and for everything below the subfile you should use separate format.
Before you show the subfile you first WRITE the other format and then you EXFMT the subfile/control.
In the DDS you will have instructed your sflctl to OVERLAY and so the three sections all show together to build your complete screen.