I have several clients who are very happy about the ability to create custom Word Layouts like for instance different layouts for sales invoices.
However they all share the same frustration that they have to assign a non-standard layout to one customer at the time. For what I've seen so far, when a custom Word layout is created, it is almost never meant for one customer only, but for a segment of customers. Could be country specific, for a specific customer price group etc.
So I think you need to add the option for BC customers to assign document layouts to multiple customers.
It could be a small feature in the report setup to set up conditions/filters for whom the specific layout should be assigned to.
Alternatively you could make it possible to assign document layouts to customer templates.