At the bottom of this page, you will see a link for BoardFAQ

In part it says...
...Next, create the body of your message and include as many relevant details as possible. Once you have typed your message, enter all of the surnames mentioned in your post in the "Surnames" field. Please include only surnames that are mentioned in your post- not all surnames you might be researching. If you wish, you can include surname spelling variations for the surnames mentioned in your message.

Board admins get a lot of abuse reports requesting deletions of surnames not mentioned in the post. They are required to delete those. However, they don't have to add surnames if a poster doesn't fill in the surname field.