Please understand that I did not mention 'vegan' with any sort of contempt. We all have our own ways of doing things. For us the challenge is getting more fruits and vegetables into the diet, though overall we are omnivores.
One of my biggest challenges was when my twins were just getting to the toddler stage. There was a nice couple in the building with a daughter about the same age that they played with in the sandbox and in play groups in each other's homes with or without other kids. The husband was Peter Singer, the Australian philosopher who at that time was writing what has become the textbook on animal rights. To be consistent, there could be no leather shoes, belts, coats, no animal protein, no feather pillows, etc. in their home. It would take me a week to figure out what I could serve them for dinner when we invited them over. We did not worry about getting animal products out of the house, only about not putting them on their dinner plates. It also would take me a bit to figure out what I could serve to Orthodox Jewish friends who kept kosher. At my house they saw a lot of kosher chicken cooked in foil and always served on paper plates and with plastic 'silverware'. When someone for philosophical or dietary reasons choses or must abide by a diet different than my own, I will honor it if I wish them to be my guest.