Entities of any kind can be regarded as simply a psychological tool that we use to make our work easier. Like, it is easier to resolve one's issues with Mom if one visualizes one's Mom and one has a conversation with her. It can be regarded completely as an imaginary exercise. It can be implied that everything we are talking about goes on in the client's mind, that is fine. It is going to work just as well, as long as the client trusts that it will.
We can also regard all entities as real live beings, just like you and I. Beings with their own completely separate existence, living a life of their own. And we can assume that there are spirits everywhere being the creative agents in any kind of activity. So, if something isn't working we would get hold of the spirit that is responsible, taking for granted that that spirit has been there all along. We can treat those entities as an objective reality and that is going to work perfectly fine.
We can adopt any model in between. We can treat all entities as part of the client, but with an certain autonomous existence. We can treat anything as simply a chunk of consciousness units out of the vast amount of consciousness that everything is made out of.
There are different existing frameworks for talking about entities. Indian shamans use certain models and a certain terminology. Jungians or Gestalt Therapists use other models, and so forth. Some people like to deal with entities as angels focusing mainly on higher dimensional entities hanging around to help.
Use whatever model works best for the client. If she already has a suitable framework you can accommodate that. If she has been wanting to talk with angels all her life, great, that is what we will help her do then. Then we can gradually expand the repertoire of what she can communicate with.