How can a man be just between his two wives regarding overnight stays if each of them lives in a different city, knowing that he permanently resides with one and only visits the other during holidays?

A husband must be just between his two wives in terms of overnight stays, even if they are in different countries, unless the wife agrees otherwise or refuses to obey him without a legitimate Shar'i excuse, in which case her right to division (of time) is forfeited. Justice and division must also be observed between the two wives during vacation periods. There is no harm if they agree that he spends it with one of them. It is preferable for the wife to be with him wherever he resides, but if that is not possible and an agreement is reached on a specific arrangement, then there is no harm.