Not sure about 240 and awards. Others here may have insights.

But a lot can happen between now and april. I would not suggest interlining with DL, though if it is offered, think of it as one of many options.

Ask UA to connect you via SFO. Would that connection work better? If not, try ATL-IAD-LAX or ATL-ORD-LAX. (I would avoid US codeshares as well for many reasons).

Between now and April, the sched. will likely change again.

Good luck!