Struggling to Transfer Old PF Accounts? How to Find Missing Details from Before 2014

I want to transfer all my previous PF from the last 15 years to my recent/latest PF. How do I identify all the past PF account numbers before 2014? [A few employers displayed PF deductions on payslips but didn't provide any PF when I transitioned and started my journey in my Indian career in the early days.]

For the existing ones where I know the PF/UAN details, should I log in to my recent/latest UAN and transfer the amount, or is there another method?

Obtaining PF Details Before UAN

The PF details before the UAN started can be obtained from the respective offices using Form 3A and the annual returns submitted. If the companies have closed and no one can be contacted, you can personally visit the EPFO's office to get the details. Once you have the PF member ID (PF account number), you can transfer the accumulation using the online platform.