Dear Mary: How can I check if my dentist uncle really meant to charge me?

Q. My uncle, who is a brilliant dentist, has looked after my teeth since I was little. He also sees my children and although he runs a private practice, he has never charged me at all. I am now pregnant with my third child and told him this on my last visit. I wonder if this could be the reason why I received a bill in the post for the consultation — my first ever. He has a new secretary. How can I find out whether the secretary has sent me the bill by mistake, or indeed whether my uncle has decided that he has to draw the line somewhere and is now going to start charging? He did not mention anything to me.
— Name withheld, Leeds

A. Send a cheque along with the bill but enclose them within a newsy letter to your uncle so you can write personal on the envelope and thereby bypass the secretary. If the cheque is cashed, you will soon find out if his policy towards charging you has changed.

Q. I recently saw my rather old-fashioned aunt shudder when I used the word sibling. Mary, can you rule? Is the word sibling acceptable?
— K.N., Oxford

A. There is no precise rule about the word sibling but you rarely hear it being used outside educational establishments without the perpetrator instinctively pulling an apologetic face. Hence it is best avoided.

Q. I am not particularly narcissistic but I have joined Instagram because it seems to me a fairly benign form of social media. It means I can stay connected with parents and old friends with minimum effort and there’s no need to write much as the pictures speak for themselves. My problem is that I share a name with somebody well known in the fashion world and often receive follow requests from people who have clearly mistaken me for her.