I got a small schedule change for an itinerary in August. Having heard the stories of the rebooking machine on the website offering fairly convoluted rebooking options, I'm be interested in trying to squeeze a few more miles out of the trip. However, I already have a plan to SDC midway through my original itinerary (which I can make with no problem), which would get me more miles than any of the proposed options on the website.

My question is this: how do fare rules govern rebookings due to schedule changes? I'm assuming that I won't have to pay a change fee (if I do in fact need to, this plan goes out the window). If I do take a different routing, would I be able to SDC mid-itinerary to get more miles, and what fare rules would govern that SDC?

The specifics are:
currently BIL-SLC-SJC-ATL-BOS, small shift in times (I think at most 15 minutes) on all flights.
hope to SDC SJC-ATL-MEM-BOS, which is a valid routing according to the fare rules
alternative options presented by the website:
SJC-LAX-ATL-BOS
SJC-PDX-MSP-BOS
SJC-LAX-MSP-BOS
SJC-SLC-ATL-BOS
(SJC-LAX operated by QX in all cases)