My wife pays CSA to her ex

My step son has recently moved out and gone to live with his father. He is 14 and decided that our rules are too strict and he wants an easy life. My wifes ex pays her £80 a month through the CSA. But now that he has moved out, she said she will tell the CSA and, as she works part time as a care worker, they can then get her to pay her ex to have him. But my question is this, Will the CSA also take into account my wage, or will they only take into account my wifes wage as she is the parent of the boy in question?