I draw both from life and photo pose series purchased from other websites.
These websites claim they cannot in their critiques display photos from other websites because of copyright restrictions. Reciprocally I assume I cannot display their photos on this website which is why I rarely show a photo ref so as not to violate the restrictions. Could you clarify what the rules are, especially with nude model photos? In our own life sessions, photos are not permitted.
When someone posts photo reference from another website, if I know the website I always credit them. If I do not see the watermark I just move for the sake of time.
Maybe in your particular case David you can complete a drawing drawn from one of the photo reference here. That would be a good option. Now I completely understand that you may not connect with my photos.
In my opinion crediting the website is basically me just giving them free advertising. I think they would like that.