It will be fine Ian, it may take the next two months to worry about it, but the actual moment of appearing naked in front of someone lasts a split moment, after that it is over, you cannot become more naked at another time. It would probably be really good if your son and granddaughter did come too. You never know you may soon become a three generation naturist family. For your daughter-in-law to feel confident to do the archery would suggest she is not suspicious of naturism, and that in many ways is the main hurdle.
I know this is an old topic, but have only just seen it. I am very comfortable naked at home and at The Naturist Foundation, even when a lot of them are clothed. Our Son is coming back to live with us. Although he knows we are naturist and it does not bother him he is not comfortable with us being naked around him. Will test the waters once he has settled in.
To Steven and Janet. This is a tough one. I lived at home for several years when I returned from my Army days before I married. While it didn't involve nudity, the house rules were my parent's rules. Should you have to change your lifestyle because of an adult child? Did you invite him back or did he ask to come back?
I hope it works out for you. As I've said elsewhere I know I'm happiest when I'm nude and the prospect of losing that freedom would not sit well with me.
Good luck!