Mark 9:40 For he who is not against us is on our side.
Just because someone is different does not mean they are doing it all wrong or working against you; it just means they are different.
The disciples came to Jesus and were upset that someone else dared to cast out demons just as Jesus had asked them to.
His response was not to discourage them for not being their own disciples but to allow them to continue doing things because they were doing it in the name of Jesus.
Working for Jesus Christ comes in many different guises and we all work together fulfilling God’s will.