This is most interesting because Alice Miller has always focused on there being a True Self.
How does one reconcile the idea of there being one versus their being many. It applies here, and in a myriad of other situations as well.
Long ago I decided to see the relation between one and many as a process. I even invented a meditation ritual to help in becoming more open to this. If you start with there being one, you can always see that there are grounds for division. So you have fragmentation. If you continue the process of fragmentation, you will get so many pieces that you have atomization. If you continue this further you get a continuous flux. But as you look at that and take it all in, you again have a singular unity.
The idea is that these distinctions lie in your own perception. There is no way of separating yourself from what you claim to perceive.
Of course this applies to things like monotheism and polytheism. But it also applies to epistemological claims to there being a singular truth, a true self, or some other fixed foundation.
Alice Miller stays with Truth and True Self. That is useful because she is trying to show that there is pervasive denial. This Truth and True self are hidden behind the wall. They exist in relation to it. But this does not mean that the concepts need to be used outside of that relation.
In ancient Egypt the idea of monotheism developed as a kind of mystical insight. This was not in any way in opposition to their historical pantheon of Netters. Rather it was just a way of understanding such. One and Many were fully compatible. This occurred in their mystery schools.
It would be later that Ikhnaton tried to impose an absolutist monotheism. Then about 80 years later we find Moses, also operating from mystical insight, and also in relation oppression, championing a counter monotheism. In the tradition which sprang from this it became an absolutist monotheism imposed by the sword. This type of absolutist monotheism still underlies western religion to this very day.
About realms that both have disjunctions and are continuous, I suggest the works of Gilles Deleuze. It is also found in many of those he writes about, like Bergson, Nietzsche, Leibniz, and Spinoza.