I have had a few kids who still took bottles at nap(however, they started when they were 8,10,12 months old!) I never had an issue with it as they all took their bottle themselves and I didn't have to sit and feed it to them. A couple of them would even have their bottle in the highchairs while I cleaned up after lunch and then I would do diaper changes and put them to bed. All 3 also took soothers so that probably helped. I know at home they all sat with mom and got rocked but they didn't here and they were fine. Eventually I just did what you did and dumped it into sippy cups and told the parents. They were fine with this but I think they still continued to get a bottle at home which was fine with me.

I did have a 2.5 year old who still got a bottle at home but at daycare he didn't. Mom sent a bottle for me to use here but I never did use it as he went to bed without it. Mom was shocked and said the only way he would nap at home was if she rocked him with it. I think it was mom who needed it but I didn't say anything lol. He was always the first one fast asleep here!

I would just ask if the parents are okay with them getting their milk in a sippy cup with their lunch and see how nap time goes.