My Wife rewards Me

I'm Chris 34 (Christen) married to Marla 32, 4 children and another on the way. I married Marla 8 years ago while working overseas and we came home and settled in our present home. Quite happy with how things were going. Then 2 years later there was trouble in homeland and her brother, father and mother died as a result, Marla was desperate to get her sister Kala 30 out to join us. Kala wasn't married as she was to look after her parents and after would go to her brother's home as a honored relative till she past away. Anyway with her brother and parents dying because of the turmoil and no way to support herself. I arranged with aid organization to get Kala out and I also arranged for her to come and live with us. She arrived with just what she was wearing, Marla got her settled into our life. Traditions are different here and Kala had no chance to find a husband, she had no dowry or skills that would help her. She could read and write and talk English with an accent. Marla knew her sisters life would be hard, so Marla decided to use an old custom. It was when a female relative of the wife is left unsupported, she joins the family as second wife. No marriage is involved and she does everything a wife does in the household. Cooking, cleaning and sexual relations as well as help raising the children. The custom had gone out of use in the late 18 hundreds, but was still used rarely in the old country. I was asked by Marla if I was willing to take Kala as my second wife. I wasn't sure mainly because I thought it would cause trouble with Marla, I said I didn't want anything to cause trouble between us. But I said I would go along with her decision, a chickens answer I know. But it gave me cover if it went pear shape as they say. Expecting Marla to take awhile to think it over, that night Marla had Kala join us in our bed and both still sleep with today. I'm lucky to have a good career and good pay as a result, I've had 3 children with Marla (one late last year) and 1 with Kala who is pregnant again. We already had 2 before Kala arrived, Kala got pregnant almost straight away after joining us in our bed and Marla got pregnant 7 months later. With Kala providing most of the sex while Marla was pregnant, she got pregnant just after Marla had our latest baby. Marla and Kala are so alike in actions and there is no problems with them sharing me. I've come to think of Kala as my wife and listen to what she says and Marla treats her as a equal partner in our marriage.