What is a healthy way to approach non-human alters?

I am supporting a spouse with DID. I am hoping to bring this topic to her therapist, but I’m just curious to get a community point of view.

When it comes to non-human alters, when does it become unhealthy to believe in their animal nature?

I can understand things like wearing ears to help an alter feel comfortable, just like perhaps a female alter in a male body wearing a wig, or something like that.

What I’m wondering about is how deep the belief goes and if it is healthy to learn to accept that the body is human, and even if the alter perceives themself to be non-human, to learn to accept that they are human. Is it inherently unhealthy or feeding into an unhealthy belief for the system and the family supporting the the system to feed into the belief that an alter is not human and treat them more like the animal than the human? Where is the line?