New roof pitched on existing.

[Ashworth1]

Last year I had part of my roof re pitched so it could be made wider for my extension on the side.(2 story)
I am about to knock through and noticed that they have put a layboard on the existing rafters that are sitting on the wall plate of the wall that needs knocking down.
I obviously need to suppor this weight. The only way I see how is by extending my rafters onto a steel . Can you extend rafters? Anyone got any good methods. It would only be by about 150 mm so it can sit on the steel . Thanks

 

[noseall]

The steel will sit beneath the wall plate and the plate will be bolted to it.

 

[Ashworth1]

The steel is already in place- welded onto another steel & Ceiling joins fitted.
The only way I see I can do it is to extend the roof rafters - can you do this ? I was thinking of running 4x2 timber along side the rafter me fitting 3x10mm bolts through them to join?