lol sorry i realise looking at it now one of the paragraphs is a bit confusing
so
on weds i saw a number of ospreys, by looking closely at the plumage (mostly the moult**) i was able to deduce the observations involved 5 different birds
on friday, similar scenario, now two of the birds i recognised from weds
so we have two ospreys - stay with me here

i aslo saw a juvenile bird (the only juvenile we have atm), so that makes 3 birds
then in the afternoon among the many osprey sightings we had a bird with a clear breastband (none of the others do), so that was the 4th bird and then a very similar bird but with a reduced breastband showed up making it the 5th bird (a mate was taking photos and we compared the two to make sure they were different birds as they were very similar)
sooooooooooo, i had two days with 5 different birds logged but they weren't the same five birds on friday as weds (tho two were) - those aren't the sightings of all the ospreys we've had just a breakdown of the two 5-bird days (the previous breakdown bit in the original post listed all the birds to date)
i hope that's more clear?

??
** imagine you see a buzzard fly past and it has clear holes in its wings, hour later buzzard again flys past you think 'oh here it is again' but it has no holes in the wings - clearly not the same bird even if the plumage looks similar
so by looking at the state of the moult (wear and feather replacement) you can often seperate individuals, tho not all the time and you need a decent view of the birds in question

i've deliberately picked a somewhat distant shot to show it can be blindingly obvious in some cases - so forget the different plumage look of these birds (lower is female, upper is male), concentrate on the back edge of the wings (what we call the trailing edge)
on the upper bird there a two very clear notches towards the end of the wing (one on each wing) that the lower bird doesn't have, so even in silhouette you'd know this isn't the same bird if you saw them apart
that's the kind of thing we're doing, combined with plumage features, bird's age and sex
it's not always possible by any means, as i said the three that banged thru quickly at distance were easy enough to see were adults but sexing them wasn't possible but im confident they didn't return to the lake cos they were really motoring as they were in migration mode (they actually fly very different than a bird staying around the lake)
for any interested in the subject there's a very informative and educational podcast type thing by the guys who have been tracking them for the past 20ish years, it's really good showing individual histories, adaptation as they age, flight paths, their wintering grounds etc (much more interesting than me and the fucking moult of various birds

)
https://www.youtube.com/watch?v=JXWgoSF-Yrkas a teaser, there's the case of a uk juvenile osprey and its first migration that goes wrong and he misses the north coast of spain (his target) and continues heading out over the atlantic, to its apparent demise after a haul of 1302km in continuous flight for 33 hours - does he make it?
there's only one way to find out......... Flight!