My older sister has schizo-affective and desires a luxurious lifestyle. She grew up in a middle-class family with a simple way of living. Currently, she is 35 years old and has one child. She separated with her husband, but not legally-divorced legally. She has a job and earns her own income, and she also owns credit card(s).
Right now, she is fulfilling her dream of a luxurious lifestyle by utilizing her credit card. When we advise her to manage her finances carefully and save for the future, she always insists that she can afford it and is capable of calculating her installment payments properly.
What worries us is that she is currently on leave from work, and in the past week, she has stayed at a hotel for eight days, spending 1.5 times her monthly salary. She also plans to do the same staycation in June and August.
While technically, she can still afford to pay in installments for the next 12 months, we are concerned that she may increasingly lose control over her spending, leading to unpaid debts—especially considering her responsibility to care for her three-year-old child. Moreover, she has previously maxed out her credit card limit and was unable to pay, forcing our parents to cover the debt.
What can we do in this situation? We have considered several options, such as giving her an ultimatum that we will not help pay her credit card debt if she fails to manage it, secretly closing her credit card, or asking her company to transfer her salary directly to our parents. However, the consequences of these actions would almost certainly lead to full-time rehabilitation which is bad for her job (she has already undergone rehabilitation for three times: in 2014 [1st break], 2016 [2nd break], and most recently in January-February 2025 [3rd break]).