Roof to Roof garage addition....

I would like to put a 16' wide addition beside my garage. The existing garage is a standard 24' X 24' footprint with 8'walls and a 5/12 pitch roof. The addition would be 16' X 22' long set back two fee from the front 2' for looks. My question is the roof. Due to needed height inside the addition 10' walls I would like to join the roofs a third of the way or so up the peek for a shed type roof with a minimum 3/12 pitch. Can anyone help me with this?
How do I join the rafters? Do I line them up with the garage trusses or do I create a kind of sill?
Any help/suggestions would be appreciated.
I can get some pics if that would be helpful.
Thanks

 

Best to tie in at the ridge I think.
Personally, I like removing all shingles and felt where I do the tie-in, and install 2 (2 each) 2X6 sills to the deck, nailed at the rafters. Allow for the decking to determine placement for the topmost sill. Figure the rafter cut, and place one in position. NOW, you will know where to put the second one for best contact with the shed rafters.
I try ti align the new rafters on top of the old, but it isn't critical if the placement is inexact.