Hello Liz

The births that Joe has found are very likely the same family. Here they are in 1851:
Parish 820 ED 7 Page 19
Townhead, Lockerbie (Dryfesdale)
John Telfer, hd, 31, labourer, b. Dryfesdale
Janet, wife, 29, b. Canonbie
William, s, 8, scholar, b. Dryfesdale
Mary, d, 5, b. Dryfesdale
Jean, d, 3, b. Dryfesdale
Agnes, d, 5 months, b. Dryfesdale
Regards
Gadget
PS I see that you are looking for 3 generations. It's probably best to do one at a time. I'll see what I can find on this generation. first!