[Greenbuilding] Porch Roof Flashing

[Dusch, Jim E]

I'm looking to do the best I can with the junction between a porch roof
(newly added) and the existing structure at an inside corner.  I realize
there's no for the fundamentals -- good roofing practices with flashing
-- but the inside corner has all kinds of challenges when existing
corner boards and funky angles are part of the picture.  I'd like to
minimize (or eliminate) use of cement/sealer but am not sure I have a
choice.

Suggestions on flashing configuration and/or eco-friendly sealer/weld
are what I need.  Thanks.