My kids' grandparents broke all the rules for babysitting: They gave them champagne and told them to lie to us.

• My husband and I left our first baby with his parents for a trip, and it was a success.
• When it came to leaving our two kids with my parents, things didn't go as well.

The first time my husband and I left our baby with my husband's parents, he was 13 months old and newly weaned. We went to Toronto for the week and returned to two tired but happy grandparents and a baby who was only slightly resentful toward the temporary abandonment. All-in-all, a complete success and something we repeated regularly once our second son was born.

But leaving the kids with my 60-year-old mom and stepfather was a different story. They loved our boys but prioritized their own entertainment and comfort. There was also a history of passive aggression when it came to ignoring our parenting choices, for example, filling their kitchen drawer with pacifiers after we told them we didn't use them or leaving a bottle of Tylenol PM in the guest bathroom for us to "cut just a sliver" to help the baby sleep when we visited.

So, it wasn't until our kids were 3 and 5 years old that we dropped the boys off for a sleepover. Things didn't go as planned.

I went over routines and what not to do with my mom

My husband and I planned to stay at a nearby hotel for a mini getaway: dinner at a restaurant, a leisurely visit to an indie bookstore, and sleeping in the next morning. At my mom's apartment, before saying goodbye to the kids, I went over bedtime routines and assurances that the kids could skip their baths.

There was also something, probably irrational, that concerned me, and I brought it up sheepishly, embarrassed, speaking with my mom privately.

"I don't want Simon to share a bed with Zaidy," I said. Our 3-year-old was tiny and incredibly thin, and I worried that my large stepfather, a sound sleeper who had never had babies of his own, might roll over in the night and crush my son.

I knew I was being overcautious, bordering on ridiculous, but my fear was real. I was asking my mom to hold my parental anxiety with kindness. Kindness, and also empathy, as a former mom of sweet, defenseless young children.

She promised me the kids would sleep in the twin beds in the guest room.

We had a blast, but my parents didn't follow our instructions

My husband and I loved every minute of our alone time, and the next day, recharged, we rejoined everyone for lunch at the apartment. My parents had taken the kids to see Cirque du Soleil, and we heard all about the music, the acrobatics, and the insect-themed costumes.

"Nana and Zaidy gave us Champagne!" our 5-year-old, Oscar, shouted. My mom made a playful "shocked" face, putting her finger to her lips. Oscar said, "We told them we aren't allowed to drink alcohol."

"Nana and Zaidy told us not to tell you," Simon said.

My mom laughed. "Shhh!" she said in a fake whisper. "That was our secret."

I was dumbfounded. Not only had my parents served our preschoolers alcohol, but they'd done so even after our incredible kids had told them they weren't allowed to drink. I said what I would have expected any adult, any grandparent, to say.

"I'm so proud of you for speaking up, for telling them the rules in our family. Nana and Zaidy should have listened to you," I responded.

Inside, I was seething, less about the sips of Champagne and much more about my mom and stepfather telling the kids it was OK to not listen to our rules. And also that it was OK, encouraged even, to keep an issue concerning their health and safety secret from us.

We got ready to leave. I've learned over the years that my mom doesn't listen well to me. Or she listens, but what she hears is very different from what I say, which is why I'd tried to be so direct when it came to the kids' sleeping arrangements at their apartment.

I packed up Oscar's clothes and stuffed animals from the guest room floor. My mom had clearly slept in one of the twin beds.

"Where are Simon's things?" I asked.

"Simon and Zaidy had a sleepover in the big bed," she said, without any recognition of my appeal from the day before. "They had a great time!"

I let the issue slide, but we didn't ask my parents to host the kids again until our boys were teenagers.