Во время упосатхи кофе пить можно с добавлением сухого молока?
Судя по текстам, это было бы нарушением шестого правила.
(6) “I accept the training rule to abstain from food at improper times.” This means that no solid food (including milk and milk products) should be consumed between twelve noon and dawn of the following day (roughly 6 am). After twelve noon, one may drink any beverage such as tea, coffee, cocoa, fruit juices, etc. A plain vegetable broth, without the pulp, is also permissible. Precept-holders should eat a more substantial lunch than usual (but without stuffing oneself!). With a little determination to resist the force of habit, one will find this suffices for the rest of the day. http://www.bodhimonastery.net/bm/precepts.html
As regards drinking, a bhikkhu may not drink distilled or fermented intoxicants (sura-meraya-majja) (except minute quantities contained in necessary medicines). Before noon any other drink may be offered to him, with or without milk. After twelve o'clock noon it is not allowable for him to take milk (or any drink containing milk), cereals, eggs, etc., nor any kind of soup. He may be offered any fruit juice (uncooked but strained and free from particles of fruit), or any of the bottled soft drinks which are now common. The five medicines allowable over a period of seven days may also be taken by him if he is indisposed. The first of these, ghee, is generally not available outside India, but the other four are common: butter (but not cheese), vegetable oil (such as margarine), honey, molasses (including all sorts of sugar). If more of these is accepted by him than he can consume in one evening, it may be kept by him for seven days at most. Any remaining after this time he cannot consume without falling into an offense. It is thus common for these "medicines" to be kept by a samanera or lay-disciple, to be offered as they are needed. Tea, coffee, and cocoa (all without milk) are also allowable during the afternoon and evening. With these allowable drinks and fortified in any case by having few desires and some ability to endure, bhikkhus (and samaneras) sustain themselves for study, practice or teaching.http://www.jendhamuni.com/buddhism/articles/FoodandDrink.htm