treat friendly? Is it correct?

[dido4]

We should treat others friendly.

Q1: Is this sentence correct? The word friendly is an adjective.
It should be an adverb to modify the verb treat. Am I right?
So how to rewrite the sentence to make the sentence correct?

Q2: Is there an adverb for friendly?

Thank you.

 

[tedmc]

We should treat others friendlily.
We should be friendly to others.

 

[teechar]

I prefer "in a friendly way" to "friendlily."

 

[Matthew Wai]

I don't know whether it is correct, but The Free Dictionary has marked 'friendly' as an adverb.

Not a teacher.

 

[MikeNewYork]

"Friendly" is used as an adverb.