Did all emigrate? - later entries are:
a Catharine Blair is in Ramsey 1889 http://www.ee.surrey.ac.uk/Contrib/manx/fulltext/pd1889/ra_crt.htm
in 1894 - Blair William, foreman iron founder, the Quay
Blair Mrs Catherine Y., private apartments, St. Hilliers, Brook-hill both in Ramsey
a James Blair was schoolmaster at Ramsey National school in 1863