Hi Monika,
maybe can you try to explain in more detail what the business background and the problem is that you want to solve?
I assume that with "customer" you do not mean the customers to which you ship to your products (so e.g. customer in outbound delivery), as here it is absolutely the normal case to have multiple customers.
Are you talking about consignment stock? So "entitled" or "owner", so that you have stock in your warehouse belongs to different customers (and is not owned by the warehouse)?
So maybe explain more in detail what you mean.
Best regards
Markus