How do I help my ADHD students pay attention

I teach music at a children's home in SE Asia. The students go to school during the day and I get them after they come home. Honestly, I think that more than half of my music students have ADHD which may be why a lot of them ended up in the children's home (parents lacking resources to know what to do with them. Most of the children are not orphans.)

So many of them I get right after they've arrived home from school, and some of them I get after they've had meditation and eaten dinner. So they're kind of crazed. There are several degrees of disorganization here so we often will have already eaten into 15-20 minutes of class time just trying to get all of the kids into the classroom (only 4 children for the specific class I'm concerned about.) So once they get here I want to get down to business, but the boys are so distracted. There are higher expectations of girls than boys in this culture, so both parties (myself and the students) are already at a disadvantage there.

Anyway, one of my students just kind of fiddles around when I'm explaining things, but he is listening while fidgeting. The other student doesn't speak any English and I don't speak his language, but it's instruction on a musical instrument so there's less English and more demonstration and vocalization, clapping, etc. But he gets so distracted with singing and playing his flute that he is not watching the explanations. And I know he's paying zero attention because when we play the part I demonstrate he makes the exact mistake I knew he was going to make.

This particular student is one of two set to move from recorder into transverse flute. Time and money both are scarce and so I feel the need to be assured in his ability to learn and practice before investing these things in him.

So how do I approach class in a way that helps to lock him in on what we're doing? He does like playing music. He likes flute, he likes to sing and dance, but I struggle to get him invested in what we're doing.

Also, as a side note, none of the children are diagnosed with ADHD. There isn't really a vehicle for that, especially not for theses kids. I, myself, have ADHD (tested and diagnosed) and it also runs rampant in my family, so I recognize the behaviours and thought processes.