Hi all, was wondering if someone here could help with identifying a couple of Yak-52s that don't have any clear indication as to what registration mark they hold.

The aircraft I'm interested in are the lead aircraft in this formation with the aftermarket 3 blade prop, and also the blue painted one. The CAA website indicates to me that the blue one is probably ZK-ZAY, based on the fact that I'm pretty sure that it's based at Pauanui Beach, and the only other Yak-52 based there is -YNZ which is, as you can see from the photo, clearly not the blue one.
If someone could confirm that it is indeed -ZAY (or otherwise) though that would be good. Can't work out which the lead aircraft is; I thought perhaps the "718" may be part of the serial number, as is sometimes the case, but that doesn't appear to be so.
Thanks in advance!

The aircraft I'm interested in are the lead aircraft in this formation with the aftermarket 3 blade prop, and also the blue painted one. The CAA website indicates to me that the blue one is probably ZK-ZAY, based on the fact that I'm pretty sure that it's based at Pauanui Beach, and the only other Yak-52 based there is -YNZ which is, as you can see from the photo, clearly not the blue one.
Thanks in advance!