Two days ago I woke up and found out my credit card was charged at 0600 in the morning on my iPhone notification centre. So I used some tools like "reportaproblem.apple.com" to check any purchase(s) and my subscriptions on my iPhone to find out what happen. I had checked a while and got no idea why my credit card was charged. So I called Apple hotline to find out. The Apple CS asked me to check my family member bought IAP whether or not and told me that they cannot check for me because it was IAP if any. I should "ASK" my family member although my credit card was charged and I had no right to check IAP thru hotline if any. I DON'T KNOW WHY I HAD NO RIGHTS TO CHECK THAT KIND OF IAP if any. WTH!!! OMG!!! 
After one day of my investigation on every family member under my family sharing (I am the family organizer), I found out that one of my family members had charged her personal iCloud plan 200GB because of she joining my family sharing plan before her next personal subscribed iCloud plan to pay. Is it the new feature of "Family Sharing"? What happen!! I had subscribed 2TB iCloud plan before with family sharing "ON".
IMO, if individual family member likes to join the family sharing plan, he/she should entitle to use all things under family sharing including iCloud plan, we have no need to choose anymore instead of not joining family sharing plan if he/she likes to use family “Personal" iCloud plan instead of using "Family" iCloud plan.
I remembered that there was no option[switch] to choose either "Personal" or "Family" iCloud plan under "Manage iCloud Storage" on iPhone under iOS 11 or 12. Why WE HAVE to CHOOSE right now?
I didn't asked Apple CS to refund that kind of payment (this payment is neither my family member nor mine fault though) which was already charged my credit card. I just reported my investigation/find-outs to Apple hotline with my case and asked them why. IS IT A BUG or NEW FEATURE? They said that this feature is "ON" since iOS 14.
This so-called new feature since iOS 14 should be meaningful to somebody, that's why Apple iOS developers are added. But in my point of view, it is meaningless. Just like I said above that if individual joins family sharing plan, he/she does not use personal iCloud plan, they want use family iCloud plan instead.
WHY THEY HAVE TO CHOOSE?
After one day of my investigation on every family member under my family sharing (I am the family organizer), I found out that one of my family members had charged her personal iCloud plan 200GB because of she joining my family sharing plan before her next personal subscribed iCloud plan to pay. Is it the new feature of "Family Sharing"? What happen!! I had subscribed 2TB iCloud plan before with family sharing "ON".
IMO, if individual family member likes to join the family sharing plan, he/she should entitle to use all things under family sharing including iCloud plan, we have no need to choose anymore instead of not joining family sharing plan if he/she likes to use family “Personal" iCloud plan instead of using "Family" iCloud plan.
I remembered that there was no option[switch] to choose either "Personal" or "Family" iCloud plan under "Manage iCloud Storage" on iPhone under iOS 11 or 12. Why WE HAVE to CHOOSE right now?
I didn't asked Apple CS to refund that kind of payment (this payment is neither my family member nor mine fault though) which was already charged my credit card. I just reported my investigation/find-outs to Apple hotline with my case and asked them why. IS IT A BUG or NEW FEATURE? They said that this feature is "ON" since iOS 14.
This so-called new feature since iOS 14 should be meaningful to somebody, that's why Apple iOS developers are added. But in my point of view, it is meaningless. Just like I said above that if individual joins family sharing plan, he/she does not use personal iCloud plan, they want use family iCloud plan instead.
WHY THEY HAVE TO CHOOSE?