not typical but not that unusual as geese are very sociable. if he's been around since they were little and wasn't aggressive with the other gander, he could be accepted. i have a fire pond near my house and there is always a couple pairs of canadians on it in the spring. when the goslings hatch, for awhile the parents keep them away from the other family but after a few weeks the goslings all inter mingle and the adults coparent. its pretty neat to see that gaggle in the middle of the pond!
Rich From London wrote:I wonder if someone with some goose knowledge could help solve a little puzzle... I live in London, on a canal, and during Covid lock down I've been watching a family of 6 goslings grow up with two Canada geese parents... and randomly, a third "parent"... a greylag goose. We've come to know him as the fun uncle. The two parents are very protective of their chicks among other geese, but fun uncle is very much included in the family. Is this normal?