3 Daughters- One Bedroom

Would love to hear from other parents who have been through this… My ex-husband (of two years now) lives in a one bedroom apartment. However, we have 3 daughters (20, 18 and 15) and joint custody (now only applies to the 15 year old). When they visit, they have to sleep in the living room. He makes a decent salary, about $55,000 a year, and pays me $432.00 a month child support. He claims he is unable to afford a larger apartment, even though his rent is less than $600 a month. Is there anything I can do to encourage him get a living arrangement that will place the girls in an actual bedroom? I have tried not to make a big deal out of it, but it seems ridiculus and the girls are uncomfortable with the situation. They have complained to him, but he just says he can not afford it, because of all the child suppport he must pay. So, even though he is supposed to have custody every other weekend, it very rarely happens, because they do not want to sleep in the living room! I do not push it at all, and have just let them stay home.