“All she has to do is reimburse your dad. Or, if she has someone else handling her finances, she can instruct that person to do so, if everyone’s in agreement,” says Mitchell Freedman, a CPA and financial advisor in Sherman Oaks, CA.

But, Freedman says, first make sure everyone is on the same page. “While one can easily understand why a son would not want his father to pay for a stepmother’s expenses, what is the father’s understanding and what is the agreement between the stepmom and Dad?”

Other questions may also pop up, he adds. “Was Dad required to be a guarantor of her medical expenses? Is there a prenuptial agreement that covers this issue? Is there medical insurance? Do they each have an estate plan? My suggestion is to seek [the counsel of] an elder law attorney.”

But a proper first step, notes Freedman, “is to answer the most relevant question: Does your father wish to pay those bills? Assuming you have a relationship with your dad in which you can have a candid discussion, you should do so.”