Dear Amy: My wife, kids and I had a wonderful time visiting recently with my sister, her new husband, and their daughter, “Evie,” at their home in Florida.

My kids love getting together with their cousin Evie.

I was very bothered that during our time there, Evie always had a vaping pen in her hand.

No matter what else she was doing, she was constantly vaping.

On several occasions, I observed her going onto the “smoking porch” with her folks and my wife, and vaping while the adults smoked.

I asked my sister why she allows Evie, who just turned 15, to do this.

She said that Evie picked up smoking from her and her husband, and they got her a vaping pen as an alternative to cigarettes.

My wife also smokes, but our kids know that there will be major consequences if they are caught smoking or vaping.

My sister and her husband want to take a cruise, and asked if Evie could stay with us. We agreed, but how do we deal with the issue with her vaping, since her parents allow it?

– Worried Uncle

Dear Worried: These parents’ choice to hook their daughter on vaping nicotine, allegedly in order to protect her from tar and other chemicals present in cigarettes is not only incomprehensible, but reprehensible. It’s like giving your child a beer to prevent her from ever wanting a gin and tonic.

It is also now illegal in all 50 states for anyone under 21 to purchase tobacco products, including vaping products.

You’ve heard the cliché: “My house, my rules?” Calmly, assuredly, and pointedly raise this in advance of the visit, sharing your non-negotiable with both “Evie” and her parents.

“We are looking forward to having Evie visit us, but don’t allow any underage person in our home to smoke in any form. That includes vaping. Evie, will you agree not to vape while you’re with us?”

If Evie does agree to spend the week with you under these terms, your wife should not smoke at all in the presence of any of these young people. Perhaps this will inspire her to cut down on her own tobacco habit.

During the week she is with you, keep the kids very busy. Communicate privately with Evie about vaping (without trashing her mother), and assume that she will hide her habit while she is with you (vaping is easy to hide, which is one reason almost half of all teens are estimated to have at least tried it).

Don’t overly police her or go through her things.

You can email Amy Dickinson at [email protected] or send a letter to Ask Amy, P.O. Box 194, Freeville, NY 13068.