She is married to John Silversides, a retired prison chaplain,[1] and has two adult children.

After attending the University of Sydney, where she became an Anglican, Blackwell studied at Moore Theological College from 1989 to 1992.

[3] On 3 December 2011 her appointment as an assistant bishop in the Diocese of Canberra and Goulburn was announced.

On 19 December 2014 it was announced that Blackwell had been appointed an assistant bishop in the Diocese of Melbourne.

[11] She was commissioned on 19 June 2015 as assistant bishop with responsibility for parishes in the city and eastern suburbs,[11] now called the Marmingatha episcopate.