You could create 2 physical files, each with 1 format, then create a logical file over the 2 physical files. When you access the logical file you can read both record formats from the 2 physical files.
A physical file or a join logical file can only have one format.
Hard to tell by your code what you are trying to accomplish.
You can’t create a physical file with more than one format because physical files are defined as having only one record format.
If you need multiple record layouts, use program described files.
This is a fundamental aspect of essentially all relational tables. Do you know of <i>any</i> relational DBMS that supports CREATE TABLE with multiple row definitions?