The spots on the back of Frank's head are a sign of a pied split. He might be split to WF also; I don't know how reliable this indicator is, but a broad halo around the cheek spot is supposed to be a sign.

He might have had some sort of malnutrition or other issue as a baby that makes his legs a little weak. I think Casey's Tsuka is like this too and he certainly got off to a rough start in life. His feather condition looks reasonable enough to me. They remind me a little of Shodu's feathers. She has a 'different' feather quality than my other birds, a little brownish looking, and much less waterproof than the rest of the flock. She's fine and healthy though.

Trilly looks fine to me. She does have very poofy face feathers but this is probably just an individual variation. She's pearl of course, I don't see any signs of a pied split.

When I got Frank from the pet shop he was alone with a bunch of budgie bullies, no signs of siblings, which was weird because they usually arrive in groups of four or five; so I have no idea if his leg condition is due to genetic inheritance or malnutrition.

He eats LOADS, forever munching on veggies and seeds, but I never was able to plump him up more than a measly 69 grams.
Probably the feathers you saw hanging on his legs are just normal feathers but since he squats that way they look like a long puffy apron.

Based on his small size, I would guess that he was probably the youngest of a large clutch. The youngest baby tends to be a little bit of a runt, because the parents adjust the thickness of their 'baby food' to meet the needs of the oldest chicks. Older babies need thicker food than younger babies, and it's harder for a younger baby to digest this thick food. So they don't grow as much. If the parents weren't getting a high-nutrition diet that would add to the problem. 69 grams is a low weight compared to the average but it might be the perfect weight for him. The best way to judge the appropriateness of a bird's weight is to feel the keel bone.

From what I can see it looks like his toes point straight ahead like they're supposed to. When the toes are weak and lay on their side when the bird stands on a flat surface, that's a definite sign of infant malnutrition.

That's funny you mentioned earlier about "hemp" seeds. I thought those weird seeds I found in my budgies food looked like seeds I remember from high school..........lol!!!

All hemp seed sold in the US has to be sterilized before sale so the seed can't germinate. They don't want people growing "that stuff" lol. But I suppose that under Colorado state law it's now legal to grow it and feed the seeds to your birds instead of using it the way most people do.

For anyone who's wondering what we're talking about, hemp is cannabis and you probably know what that means. But the hemp that's used to produce seed, oil, and rope fiber isn't the most smokable kind.