I had the same question, and got my answer from
ERAS, see below or the link:
Application Process Guideline
Step 11: Add Programs/Update Your Documents and Track Assignments
You may apply to additional programs at any time. Use the Program Search tab to make additional selections just as you did previously and do not forget to make your document assignments before you transmit the applications.
If the programs added are within the first 10 applications per specialty covered in the ERAS fee, you will not be charged additional fees.
Changes to Documents and Document Assignments
* At any time, you may change your LoR and personal statement assignments.
* You may de-assign a personal statement from a program and assign a new personal statement in its place.
* You may de-assign LoRs from a program and assign new ones in their place.
Note: If a program has already downloaded a document that you de-assign, they may have printed out a hard copy. Do not assume they will not be able to reference it in the future.
* Changes to document assignments or track selections for programs that have been previously applied to are submitted immediately.
Best of luck to you, this is a scary time!
🙂