On one episode of Ghost Hunters, the guys made contact with a young boy who had gotten killed while working in a textile mill and they found out the he was lonely. He was the only little kid there. Jason told him that he could come home with him because he had a lot of kids to keep him company. Maybe the child playing tricks with your wife is just lonely. I've heard that to the spirits, our night is their day; and vice versa. Maybe you could put out a light weight ball for him / her to play with that wouldn't use up their energy too fast.
Anyway, as long as the spirits are friendly, why not make them part of the family? Just tell they very forceably that there will be NO dangerous or hurtful tricks played and they are welcomed to stay and all MEAN spirits must leave.
Without going into a lot of detail here, I believe in the spirit world and a neighbor lady who passed over several years ago used to stop by to say Hi by making the smell of blueberry pie. When she was still on this side, she brought several blueberry pies to us, at different times, after she found out that my Dad liked them. One of my Uncles, who passed over in my old bedroom from throat cancer, used to come by and leave the smell of cigarette smoke. He was a lifelong smoker of Pall-Mall non filtered. That plus whiskey was the root of his cancer. He was one of my favorite uncles.....he was cool.
After my Dad pass over from Parkinson's about 3 years ago, he has stopped by a few times, too. He showed my Mom where she'd dropped a $20 bill and it slid under the couch. My Mom thought she'd dropped a $1 bill and couldn't find the thing that day. The next day, when she walked into the livingroom, the end of the $20 was peeking out from the front of the couch skirting, in the same area where she had looked the day before. Her wall clock that is a windup pendulum type clock, stopped 2 times in a row at the same time.........17 minutes before 1 o'clock. We THINK that is the time he crossed over. When his Hospice nurse came by at 6 A.M. , she found he was "gone". My Mom had thought he was just sleeping good and just adjusted his bed covers. Rigor had already thouroughly set in, so he'd been gone for a few hours.