>>I had so many honorary aunts and uncles that I was well into my teens before I managed to sort out who was what. <<

Me, too, rhapsody lute, aka lusy. The practise was common in Rhodesia (can't get used to calling my native land Zimbabwe), and it still applies in South Africa, amongst both English and Afrikaans speakers.

I dislike the custom and encourage my children's friends to call me David. My nephews/nieces call me "Uncle David" only when they want to annoy me!

Is there a collective/descriptive noun for nieces/nephews?