The forces for parts 1 and 2 are calculated on strain compatibility for each part. The summation for this isn't essentially the bending moment for the total part. Also, the forces of part 1 and part 2 are of no engineering significance. This bifurcation of parts is mainly for stress results. Hence, as a general guideline, when checking the force results, it is always advisable to check for the Total and when checking the stresses, it is always advisable to check for individual parts.