ich würde gern bitte das neue Abonoment meiner schwegerin übertragen
You can simply change the email address associated with your Bitdefender Central account to your sister-in-law's email. However, make sure that your sister-in-law does not already have a Bitdefender Central account linked to her current email.
To change the email address of the Bitdefender Central account, kindly refer to the link provided below
https://www.bitdefender.com/consumer/support/answer/13002/
Regards