In most countries, a man can't have more than one wife. In Turkey, polygamy is banned. In Pakistan, if a man wants to take a second wife, he has to get written permission from his current wife, who has no choice but to agree, as she knows he will divorce her if she says no. 

Muslims living in the UK have found a way to practice polygamy without being arrested. They can't divorce their current wives because they would have to give her half their properties and incomes, without having full custody of their children. So they have an Islamic marriage in a mosque. The second wife doesn't object, she's already a British citizen and even if she has children without being legally married, the state cannot punish her. In fact, her children will also get UK citizenship.

During my recent vacation in England, a ten year old girl (Sarah) was killed, and her father (with his second wife called "partner") escaped to Pakistan. They are now back in the UK, facing trial for murder of the little girl. Her biological mother is Polish, and her father evidently didn't want to divorce her (for reasons cited above). So he married a British Pakistani woman without divorcing the first wife.  I can guess why he killed his daughter. He probably wanted her to go to Pakistan with him so she could be engaged to one of his nephews. I suspect that when she refused, he got enraged and beat her up. I hope he and his "partner" are sentenced to life imprisonment.