Does anyone know if you can use the first day of the 2fer ticket at DCA, then use the second day at Disneyland. Or do they require you to go the Disneyland first, then use the second day at DCA? I have an AP, but my sis doesn't and we will be going in early April, but want to go to DCA on day one since we'll be arriving later that day, and want to spend a good long full day at Disneyland.

Whichever way you want.

You can use the 2fer at DL or DCA the first time then the OTHER Park the second time. You cannot use it to go to DL twice or DCA twice. Does not matter which Park you use it at first.
DPC