According to Helman's tweet, the trio of Morris, McFadden, and Smith will all be involved in the Cowboys' run game in the absence of the suspended Ezekiel Elliott. However, there is no specific breakdown of how the workload will be split between the three.
We kind of expected this, as there has been talk of all three backs being involved in the run game. We most likely won't get any clarity on the situation until we see the Cowboys play a game without Elliott, but look to Morris to handle early-down work, while McFadden is involved in passing downs. Smith is the wildcard here.
We have Morris ranked the highest of the three Cowboys backs this week (No. 17 RB in standard leagues, No. 25 RB in PPR leagues).