To tell you the truth, handling a multi-restriction arrival is not the strength of our current iteration FMS... The real plane does handle that a bit better - and we are planning to get there.
To save yourself the frustration for now, do what real pilots do - don´t try to micromanage your descent with the FMS, but do the math in your head and fly the airplane, instead of having it fly you.
This may sound like a lame excuse, and I understand that simulator pilots are obsessed with the fully managed flight - it is my fault that we have built the plane with the real pilots priorities in mind, and not the simulator crowd. We fully plan to flesh the VNAV part out in the future - but rest assured, if you get 100 real 737 pilots into a discussion about what VNAV will do during the descent, 98% will sigh, roll their eyes and twitch their shoulders up . And I was one of the 2 remaining ones that had at least a vague idea...
Fly, don´t code!
Cheers, Jan