How to prepay and request a ride for family member
The Guru Take
Yes, you can. Not so much prepay, but can charge your credit card.
What a nice gesture! and it's a great way to simply the finances and logistics within your family. Here are the answers to your questions.
If you are requesting a ride for a family member using your Uber account, the charge will automatically go to your credit card on file. The family member will not have to pay for the ride. This isn't "prepaying", but I believe it accomplishes your goal where your family does not have to worry about the payments.
You could potentially purchase an Uber gift card and give it as a gift, but then you wouldn't be doing the second part of your question.
2) Requesting a ride for a family member
You can call for an Uber for someone else, using your app. Here are the instructions: