For milking, the biggest issue is that you're converting food edible for humans into food edible for humans. So the only profit comes from the type of food that it is.
I'm not entirely certain, but I believe it's possibly to make the mother's body think there are more babies to feed. In fact, women who aren't pregnant can lactate to nurse a baby in case the mother dies. Knowing that and assuming simulated milk production for triplets when there's actually only 1 kid, that'd give us a surplus of 1000 to 2000 mL a day per mother.
Thinking about it, it could give players a late-game sink for all that food they have in surplus. All that venison, all that tender rabbit meat... Meals that give bonuses were a suggestion but lactating mothers in another. It takes quite a lot of calories for a mother to lactate, that means they need more food if they are to produce that milk surplus. Give MC a milk barn and stash cooked food in there so that every day, every mother can eat her fill (and reduced or no surplus milk production at all if MC fails to do so).
And of course, they'd have to actually go to the barn once per day (for an hour). Whether that's Chyos deciding for each one when in their schedule they go pump themselves or whether it's players... Well, I think it'd be better to leave it to the players. Let's say you only start with 1 available slot at first (so only 1 can pump her teats each hour) then increase the number of slots. If the schedules were fixed (Emily is always at 9 am, etc), there could be 2 schedules for the same hour. That means you'd be arbitrarily losing 1 pair of udders to get milk from, even though you would imply tell her to come the next hour. And I think it'd be better to improve the barn over time instead of it being a one-time thing and boom, you can pump as many women as you want!
... Where was I going with all this again? I don't know, I want to sleep. I'm not even sure I'm making sense anymore. But yeah, that milking idea could work. It could also give us a breastplay scene to "stimulate lactation" (and potentially more) for every girl prior to allowing them to get milked. A scene that could be repeated. To make sure they keep lactating, of course.
Now I'm curious what your thoughts might be... I find the logistics of a human milk barn amusing to figure out, since they do have the big problem of converting food into food... which isn't really a good deal at all when you think about it. It's like: give me 10 bucks, I'll give you back 5
