I think there are some transcription problems with the 1871 census. Findmypast has them all as Mcfin with the three children - Marion, Archd and Isabella showing as sons and daughters of Daniel and Isabella. Using the index to Scotlandspeople they seem to be transcribed as McLin with the three young family members transcribed as Archd, Marion and Isabella. Think the original would be worth a look to try and ascertain exactly what it says.
Isobel