Need to mention that all of them have different payment methods attached to them.
???
It is not possible for subscriptions to have different payment methods. Apple use fixed criteria for how payments are charged and you cannot designate a particular method for a particular subscription. you can play with the system in terms of primary payment method at a time when a subscription is due, but that's the only way.
this support article --> How apps, content, and subscriptions from Apple are billed - Apple Support
"Which payment method is charged?
When you buy items or pay for subscriptions, Apple automatically attempts to charge your payment methods in this order:
1. Apple attempts to use your Apple ID balance to cover the full amount.
2. If you don't have Apple ID balance, you don't have enough to cover the full amount, or an item cannot be paid for with Apple ID balance, Apple attempts to charge your primary payment method (typically a credit or debit card, but varies according to country). The primary payment method is at the top of the list in Settings on your iPhone. You can control which payment method is at the top of the list. [See: Add a payment method to your Apple ID - Apple Support ]
3. If there's a problem with the primary payment method, or if the primary payment method can't be charged for the full remaining amount, Apple attempts to charge your other payment methods in order from top to bottom. If none of them can be charged, Apple may try again." See also sections B and H of Legal - Apple Media Services - Apple
Some purchases aren’t charged to your Apple ID balance
● If you're in a Family Sharing group, purchases are charged to your personal Apple ID balance. If you don't have enough Apple ID balance to pay for the purchase, the remainder is charged to the family organizer's primary payment method.
● You can’t charge gifts to your Apple ID balance. If you send a gift or gift card, your primary payment method is charged.
● Some subscriptions might not be charged to your Apple ID balance.
If none of your payment methods can be charged
If a purchase can't be charged to any of your payment methods, your account has a negative balance. You can't buy more items or update your apps until you update your payment method."
See this article about updating payment methods on various platforms (iPhone, Mac, etc.): If you need to change or update your Apple ID payment method - Apple Support
"If you change your address, the credit or debit card information that you use with your Apple ID might be automatically updated by your financial institution, and you don't need to take action. But if there's an issue [such as you having a subscription or being a Family Sharing Organizer], add a new card first, then remove the old card."
Here is how you update your payment method on an iPhone or iPad:
1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping (formerly Media & Purchases). You might be asked to sign in with your Apple ID.
4. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Delete.
