Why don't you start switching her to the dairy lactation pellets now? You need to transition slowly off the old feed anyway.
Alfalfa pellets on the milk stand is a good idea too. Our girls are milking so heavily, we just give them more grain if they finish before we do - OTOH, my daughters are super talented at milking and we breed for ease of milking, so we may milk for a shorter time and get twice as much milk (once you get much better at the milking - and the doe- , it is astonishing how quickly this chore can be done, LOL).
I am going to be the "mean" one and ask what you are raising the wethers for? That milk they are eating is more valuable than any meat you will get off of the kids, if they were being raised to butcher. You could butcher them now, put them in the freezer and then all of the milk will be for your family.
Future trick - make sure you purchase a goat with excellent milking lines if you want more milk. Unless you are prepared to spend a pretty penny for a high milking Nubian, a Swiss breed will fill your pail and feed her babies.
Patty (on this board) has beautiful Saanens in New York. CAE negative and boy can her girls milk. Perhaps when you are ready to add another goat to your mix, you might consider contacting Patty.