Hi I had this problem with Mum and found several soiled pairs stuffed under cupboards, in shoes in the wardrobe and under the mattress. I took the step of moving her onto pull up pants, explaining it was just in case she couldn't get to the loo in the night. She accepted this for the nights and after a while now also uses them for daytime too. At least this way we no longer make discoveries of unpleasant little knicker parcels in unlikely places!