Suica

If I purchase 5 physical suica cards for 5 people with a credit card, can only my credit card reload funds on those cards? Thank you!

I don't think it is possible to purchase and charge physical Suica cards with credit cards (except JR East credit cards). Welcome to Japan!

I am know sure if I got your question right, but usually it works like this:

You buy a suica card and will later top it up at a ticket-machine however and whenever you like.

It does not matter how the card was paid for.

For regular SUICA cards, anyone can use cash to load more credits using loading vending machines.

You can use a debit card (not a credit card, as a cash advance will cost you dearly) to withdraw cash from an ATM and then use the cash to buy and recharge your Suica card. I always do a travel advisory with my debit card company (bank) before I leave on my trip, and I use postal ATMs to take money out, as they only charge a small fee. 7-11 ATMs are apparently similar.

Because of supply issues, they may not allow you to buy five Suica cards at once, unless maybe you have the other people with you and they can see that you are making a single purchase for all of them. It is good news that they are now selling physical Suica cards again, period. I can’t imagine not having a physical IC card while traveling around Japan. I use mine for small purchases as often as I can (a few stores don’t take them) and it makes life so much easier…

You can add funds using cash.