Is there any way to add funds to my Apple ID without using the family organisers card?

My Apple ID is part of a family sharing setup. We use payment sharing to share an Apple One subscription, with the money coming from the family organiser's card.

The issue is, when I try to buy anything (iTunes, App store, etc), I don't have an option to select which card I want to use.

I've read that I can do so by turning off payment sharing, but I think that would also remove my access to the Apple One subscription. And, I don't seem to have the option to turn it off in the first place in settings that I can find. I'm 14 and my Apple ID is set as such, so I assume that's what's causing that.

The only viable method I can find is buying gift cards every time I want to add to my balance, which I can do, but that's obviously not ideal.

Is there any way to add funds to my Apple ID without using the family organisers card?

[Re-Titled by Moderator]