I am sorry Honeythorn, but I get very little consolation from doing what you suggest. I would much rather get the OP involved in a real give and take of information. In the long run, a good exchange of information is the best of all worlds.
At the end of the day there are only so many times you can badger at someone to do things the correct way before they look at you, shake their head and say " I think it looks fine I'm going to carry on as I am " . If her friend refuses to listen and will not take the advice then pestering constantly will only make her more determined to carry on keeping the fish badly.
If the goldfish are still very small then a pair swimming around in a ten gallon may look fine to those not in the know. Her friend seems to be one of these people going by what's been said so far. If that is the case and the fish are still small, then her friend is less likely to believe that these fish grow into a large and active commitment that reqires a lot of space and dilligent care, espescially if she has kept goldfish before and had them die (probably due to incorrect care and tiny tank size) before they've had a chance to grow into full sized adults.
This seems to be a common thing with many goldfish owners who go by shop reccomendations and past "experience" . They get a bowl or small tank, get a goldfish, it lives for a few months, maybe even a few short years,
it's growth is stunted because of the small tank size . Naturally if all these people have ever seen is a small stunted goldfish living in a bowl and think this is a normal size and way of keeping them, then they are not going to be entirely likely to believe you when you say "hey you're doing that wrong, these are the facts "
Unless the OP can find some place that keeps their goldfish correctly in a very large tank or pond, and shows the large healthy fish to her friend, then the chances of her friend taking the advice are not great.
I hate to see a fish suffer as much as anyone else, and goldfish being kept incorrectly in tiny tanks ( along with bettas ) are among my greatest blood boiling situations to observe. But if the owner refuses to listen, sometimes you have to let them get on with it. You have to let them fail and then , when you say I told you so, you can again show them the correct way of doing things, yet again try to help them and sometimes their failure can make them more open to suggestions. The thought of " well it didn't work, she said it wouldn't, I wonder if trying the way she say's will work after all " can often work far better than endless badgering to do things differently.
Look at the quote:
She doesn't want to learn; that is her problem. unsure.gif She refused to believe it when I told her Bettas need *at least* 2.5-gallons of space (preferably 5 good.gif ) and that they need heaters....
Someone like that is not going to listen to endless pleas to do things right. She doesn't want to admit she's doing things wrong. As horrible as things are ( and they will get worse) her friend
needs to fail before she will see sense.