We have a client in need of a data lake on the cloud.
We need to provide the client the chance to breakdown costs between their areas in just one AWS Account.
We are talking about query and data transfer costs also.
You can achieve this, at least most of it, with so calle dcost allocation tags:
https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/cost-alloc-tags.html
It is a way of assigning tags to resources that allows you to split up costs later on in the Cost explorer, allowing you to see a projects or "areas" share of the overall cost.
But not everything can be tagged yet, so there might be "blind spots" where you do not have data. You could split up the remaining difference evenly between all areas.