Replacing sheet T1-11 siding. Old (rotted) siding at a roof to wall juncture is glued to the old continuous steel flashing with roofing cement. The flashing was installed over the siding. I need to remove the siding and the plan was to gracefully and quickly disengage it from the flashing, slide the old flashing out from under the roof shingles, replace with aluminum step flashing, put the T1-11 over the flashing, and re-adhere the shingles to the flashing and each other. I have a limited window of time to do this in and it's getting complicated lifting the old shingles because the shingles are threatening to break, and I'm not sure it'll be easier in hot weather. It's been in the 40s at night, maybe the shingles would be less fragile in hot weather? I'm wondering about NOT replacing the flashing (assuming I can get the remaining old siding off the back of it), putting up a new flashing overlapping the old flashing down only to the level of the shingles (under the siding but not under the shingles), and sealing the new flashing to the shingles - or at least to the old flashing. Make any sense, or any other ideas? I guess another alternative is removing the old shingles and replacing them, but the roof is getting old and they will be difficult to match color.