By 1871 Mary Barret is on her own with her family
There is a death for a Michael Barret 1865 age 40 in Selkirk mothers maiden name Loftus
Which is a possibility not seeing a marriage so far maybe they married in Ireland ?
1871 address 17,Market Street Selkirk
Mary 37 born Ireland ..
Mary 19,Margaret 17,Bridget 15,Robert 11,Ellen 8
There is also a birth for a Helen Barret 1863 in Selkirk getting a copy of this should give you the parents date of marriage
Rosie