Currently, at Ashbridge’s Bay, there is a female Green-winged Teal who has clearly been welcomed into a family of Mallards.
I imagine the that teal got separated from others on their way south and was looking for a group to join for company and protection. Mallards are very trusting and were happy to welcome this little duck into their flock.
In 2016, I made a post of Mallard/Wood Duck romance.
And there will I keep you forever,
Yes, forever and a day,
Till the walls shall crumble to ruin,
And moulder in dust away! – Henry Wadsworth Longfellow