IME multi-city booking now on delta.dumb only shows you combinations of flights that aren't connections (more than 4/24 hours for domestic/international), but you should be able to call and have a DL phone agent put together the segments you want, assuming that they don't violate MCT. You might even be able to get a through fare rather than buying each segment as a separate fare (point to point pricing).

A good real live human TA should also be able to do this, but a ticketing fee will be charged.