roof bracing

We are planning an extension that will abut to our pitched roof. This will involve cutting back rafters and replacing the roof plate with an I-Beam. I would like to understand how this should be installed to continue to support existing rafters please. The below shows 2 options of how I envisage...

So I am in the process of building a roof for my future home, my wife has opted for a fan truss with vaulted ceilings. The trusses are spaced at 3.1m on center and we are using lipped channel as brandering for the roof. As well as attaching trusses together. What additional...