Back after a (very!) long time. I have found out quite a bit more in the mean time. I now know that the people in Drainie in 1881 are indeed the wife and child of my great great grandfather, and her parents. The child Lewis (Luis) was ill at the time, and the father was away at sea at the time, so (I assume) she went to be with her parents in Lossiemouth. Luis in fact died 5 days after the census was taken. The mis-spelling of the names was due to the fact that the Edward (mother's) family were illiterate, and the father was away at sea.
Moving on, I am now trying to find out about the father's arrival in Peterhead. His name was Charles Luis Liebnitz, born in Memel, Prussia around 1850. We are told he and his brother arrived together as youngsters (possibly 12 and 9), although I can't find any record in previous census. I know the brother (possibly Henry) ended up in Wales. I also know that they were helped by the local scoolmaster and minister when they arrived, including sending and receiving letters to and from their family back in Memel. Unfortunately we have no records of this. Any advice on where/how to pursue this would be much appreciated.
Thanks
Andy.