I had this when i was 21 (many yrs ago!), when i was a nanny. I was looking after a 2, 4 & 6yr old. We used to go to the library and when ever i asked the libraians for help they were really snotty towards me and unhelpful. They told to the 6yr old one day to 'give it to your mum' and looked at me. The 6yr old turned round and said (rather rudely) 'she is not my mum she is my nanny and she does lots of nice things with us and you are very rude to us so we will be going to another library next time' ! Honestly i felt quite smug when we left!!
I also nannyed a 5mth old and my dd was 6mths. They looked very similar when they were in the double buggy together. People would stop me and say 'aww how old are they?' I would point and say 'shes 5 mths, shes 6 mths' cue confused looks and me saying 'its a medical miracle!' .