Nest Envy?

When I went out to do my regular check out, nobody was there.  We hung around for a while, and then a female returned, flew around and departed. 

Shortly thereafter, a male came by and landed in the nest to be met by a female.

I say "A male and A female", because within 10 minutes, there were 4 Ospreys twisting and turning in the sky above and around the nest!

So this begs the question..welcoming committee?  Another couple trying to take over the nest?  Jealousy?  What makes this especially interesting is when I try and look closely, I can not find any photos with two identifiable males in them...