Data vault for multiple electronic medical records systems

Hi,

I’m trying to create a data vault for multiple source systems, every EMR system treat encounter as an example separately
EMR (1) encounter classified as specific document types or visits with specific billing codes
EMR(2) encounter table

Sources tables
1- document
2-document type
3- visit
4- visit procedure
5- encounter
In the raw vault should I create the hub from the combination of the business key of the tables knowing I will have to use reference tables to filter documents and billing codes as hard rule or should they be 3 hubs (document , visit, encounter) and classifying them will be BV issue ?
Thanks for the insights