Hello , Does anyone know how to add beneficieries to our account ?

There is no such possibility. You will need to check that with your legal counsel.

Contact your estate planner/attorney.

If an Adobe Stock Contributor dies, their account will typically be deactivated, content will no longer be available for purchase on the platform. 

The legal representatives of the deceased contributor should contact Adobe to discuss options regarding the content, which may include:

• Removing the content.
  
• Transferring ownership, if permitted by local laws.