1,2     House number + 20.
3,4     Last number - 50.
5,6    Last number +1.
7,8    Bretts old house number.


1,2,3    First three integers.
4          Repeat the first.
5          Itself.
6,7       Reverse them.
8          So this and the 7th are from funny password. 


1,2,3,4 Brightest observed supernova
5,6,7,8 China Overseas Property Holdings Ltd. hkg. (Ignore leading zero)

        x4
2         Last number of klb pw
3,4      House number +1
5,6,7,8    MMC (Mrs McDonald could help)