Two questions

I know this is valid for award travel:
ORD-DFW stopover
DFW-MIA stopover
MIA-DFW end

1) Once the ticket is issued, but travel has not begun, can the destination of MIA be changed (i.e. for LAX) (for the $100 fee--assuming award availability).

2) Once travel has begun (ORD-DFW) can the DFW-MIA-DFW be changed to DFW-LAX-DFW