Here’s my final answer.
1. Create file B
2. ADDLFM (add logical file member )to file AL1 named BL1 target file B
3. OVRDBF A to B
4. OVRDBF AL1 to AL1 member BL1
5. Call RPG program
6. DLTOVR A, AL1
6. RMVM BL1 from file AL1
7. DLTF B
Use CHGLF AL1 to set max number of members to 2 or more
then do these instructions. Working with two physical files B and B2 isn’t right.