Hi Melanie
Unfortunately I think you will probably struggle with this.
Do you have the details of the Dams and Sires of your ewes and if so, are BOTH parents registered? If one or both of the parents are not registered I doubt it would be possible to get your girlies registered as the DSBA is pretty strict in order to ensure that the breed remains true to type.
If they can't be registered then their offspring would not be eligible for registration either - even if the ram was registered. Doesn't however mean you can't have 'pure-bred' GFD's it just means they would not be registered and therefore would be less valuable. If you just want them for your own pleasure, does registration really matter?
Have a chat with Patrick the breed secretary - details in below link
http://www.greyface-dartmoor.org.uk/contact.html Good luck - and in the meantime enjoy your beautiful girls!