The new support for multiple customers per project is great, but currently it's not possible to switch to "Multiple Customers" if project entries already exist. This is too restrictive.

Suggestion:

Allow switching to "Multiple Customers" even if entries exist, but lock the customer on existing tasks with entries. New tasks can then be created with different customers.

This would maintain financial consistency while supporting real-world scenarios where a project starts with one customer but later involves others.