First, the OVRDBF needs to be done before the file is opened. Unless you are doing a user-open in RPG1, the file is already open before the OVRDBF.
Second, OVRDBF generally has no affect on programs at a lower call level.
If you can do the OVRDBF in CL1, RPG1 should open the correct file. If the OVRDBF has to be done in CL2, set the OVRSCOPE parameter to *JOB, and define your file in RPG1 as “User Open” and then open it following the call to CL2.