You don't put new birds in a loft with birds you already have. You should first quarantine them for 30 days to make sure all are healthy. People have infected their whole loft from bringing in new birds that were carrying illness. Good way to lose birds.
You didn't say what kind of fancy pigeon you have, but I would say no, as fancy pigeons are not bred for flying. They are not going to keep up with flying breeds.
Life isn't about waiting for the storm to pass........It's about learning to dance in the rain.