nights

Q: My husband spends 4 nights with his first wife and 3 nights with me. Out of one of the 4 nights with his first wife, he sleeps in a separate bed in another room but under the same roof. Is that counted as 4 nights or 3 nights?

Q: Can you explain the method of equal distribution of time between wives and does equality of time extend to the day as well or is it restricted to the night? Similarly, could you inform me from what time till what time is it considered night? Does it end at Subah Saadiq or sunrise?