If a co-wife stays in the hospital or goes to visit her family, does she forfeit her right to a share of her husband’s time?
Question

                I have a question about treating co-wives fairly. 

1 – If one of them falls sick and stays in the hospital for five days, and during this time I stay with the other wife, do I have to make up the same number of days? 

2 – If one of them goes to visit her family for a few days, does she have the right to ask for me to stay with her for the same number of days?.
Praise be to Allah.
    Firstly: 

    If the wife falls sick and stays in the hospital for a few 
    days, she does not have the right to a share of your time during these days, 
    because the cancellation of her rights comes from her, and obliging her 
    husband to give her a share of his time will harm him as he would have to 
    stay with her in the hospital to give her her share of his time. 

    This is known from the discussion of the fuqaha’ concerning 
    the share of the husband’s time for a co-wife who is detained. And they 
    said: A sick co-wife has the right to her share of her husband’s time, 
    unless he travels with his wives but she stayed behind because of her 
    sickness, in which case she has no right to a share of his time. Nihaayat 
    al-Muhtaaj (6/380). 

    If giving her a share of his time is waived, making it up is 
    also waived, so the husband does not have to make up those days during which 
    she was absent.  

    Secondly: 

    If the wife goes to visit her family for a few days, or she 
    travels someplace, if that is for her need, then the husband does not have 
    to make up that time for her. If it was because of his need, then he should 
    make it up for her. 

    It says in al-Mawsoo’ah al-Fiqhiyyah (33/202): The 
    share of one of them (the wives) may be missed because she is travelling. In 
    that case it depends, according to the Shaafa’is and Hanbalis. They said: If 
    she travelled without his permission for her need or his need, or for some 
    other reason, she has no right to get a share of his time, because dividing 
    of time is for the purpose of keeping company, and that is not possible in 
    this case , because of her action, therefore her right is waived. 

    If she travels with his permission and on an errand for him, 
    then he should make up the time for her,  allocating to her the same amount 
    of time as he spent with her co-wife, because she travelled with his 
    permission and on an errand for him. Her case is similar to that of a 
    co-wife who is with him but he kept away from her when he sent her away.  

    If she travelled with his permission for her own errand or 
    need, he does not have to make it up for her (according to the Hanbalis and 
    the new view of the Shaafa’is) because she caused him to miss intimacy with 
    her and she was not with him, his consent for her to travel absolves her of 
    any sin. 

    If she travels on her own with his permission for both their 
    need, her right is not waived, as al-Zarkashi and others said, with regard 
    to maintenance and also the division of his time, unlike the view of Ibn 
    al-Aymad.  End quote. 

    See: al-Sharh al-Mumti’ (12/433) 

    And Allaah knows best.