When I was on the Oosterdam, traveling solo, I left an extra $2 on the pillow of the unmade bed everyday. The room stewart worked hard at keeping the room in order. I felt I was rewarding excellent service to one individual deserving of it. I know he appreciated the "extra" he found each day. Through brief conversations I learned he had a wife and three kids which he hadn't seen in 5 months. Personally, I hope he didn't pool the money.
However, I would definitely have charges removed for any amount charged for the 3 yrs. old child.