I would definitely not add a new angelfish to a tank with angelfish already in it unless they are all still sexually immature.
In the wild they are a shoaling species - so they are a social species.
However, captivity, sexual maturity & the sex of the individual fish all have fairly dramatic effects on how they behave in the average home tank.
Unless there is a rather vast amount of space (much more than most of us could ever do more than dream about) their territoriality makes it very unlikely that a new introduction will be accepted. Usually it will get beaten up at best, killed at worst.