My winged people just have feathers on their wings, and maybe small feathers on their back between their wings (from shoulder blades to mid back). Their bodies look generally human.
Here is a link to an image I am basing their structure off of: https://blue-hearts.deviantart.com/art/SB-New-Bones-577558072
My research has gathered that birds need to preen to get rid of parasites that could carry diseases, and also to keep their feathers flexible. They also preen to arrange their feathers in the best and most aerodynamic position for flight, which makes flying easier. They have a preen gland by their tail that either produces preen oil or powder (my hybrid race will have oil because it's better for what they'll need). If birds can't reach certain places (e.g. sometimes the top of their head) they will get a bald spot and the feathers will eventually grow back.
So as you see, preening is essential to healthy wings. My question is: will the hybrids be able to apply the oil to every part of their wings (including their back between the shoulder blades) and arrange every feather just using their hands, considering the limitations of the human arms, or will I have to give them something like longer limbs to be able to reach every spot.