My family and I am happy to get the prize.
My family and I are happy for getting the prize.
Which is better, happy to or happy for?
happy to for your context. happy for has a different meaning. Consider this example.
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happy to for your context.
happy for has a different meaning.
Consider this example.
Tom was happy to get the prize.
Mary was happy for Tom.
This means Mary was happy because Tom got his prize.
The first one is OK. The second one is not natural.
Some people might say "My family and I are happy for the prize". This is not something I would personally very naturally say.
happy for can also be used when you are pleased that a good thing has happened to someone else:
"I heard you got married. I'm so happy for you!"
happy for X