Spluch points to this
BBC story. Lambs 'Lucky' and 'Charms' - those are the actual names - were born but had complications after birth, which meant they had to be separated from their mother. In stepped Molly the Rottweiler, who took to the job of licking them all over, which is the normal ewe behavior to encourage circulation in the youngsters. Molly completely adopted the pair and watches over them until they are old enough to be released to the usual field.