Domesticated female duck cozying up to nesting goose?

Hello! I have a question about the behavior of a few birds at my farm.

We took in a semi-domesticated duck from a hoarding situation to live wild on our land. Reba is about a year old, a Mallard-Peking cross. She survived a bout of bird flu that killed 9 of her other rescued companions, as well as a predator attack that took the rest. She has been the only duck on our pond for about 4 months now. She is human-friendly but still mostly wild.

We have had dozens of Canadian geese on our pond for years. One particular pair comes to the same spot to nest, on a protected little island. Mama goose is currently on the nest, while her male partner basically spends all day napping hundreds of meters away from her.

We noticed that as soon as the goose began nesting, our Reba duck spends almost all of her day on the island, watching over the goose and her nest. Reba comes to me twice a day looking for food, but other than that and a few swims, she is hovering around mama goose. Mama goose tolerates this with no aggression that we have noticed.

I'm curious if this interspecies interaction is normal? Will Reba be part of the flock once the babies hatch? I feel like she's a nanny in training, waiting for her babies to arrive. :) Any thoughts on how this might play out once the babies arrive would be appreciated!