The two in the upper right are definitely a nesting pair based on their behavior. It’s been enjoyable to have this opportunity to watch the gathering of these interesting birds.
The male hopped over to an adjacent nest, picked around a bit, and plucked a selection and returned to the other nest.
The twig is delivered to the nest that the female has clearly preferred. This suggests that the last mating pair to arrive inherits the last ratty nest in the heronry.