Hi Simon,
I have two reads for you and some thoughts. Let's start with the reads:
docs.microsoft.com/.../data-sharing-customer-vendor-tables
dynamicspedia.com/.../
The blog 'To share or not to share' is based on AX2012, but still applicable to Dynamics 365 as the data model is hardly changed for the vendor master data.
However, there are actually changes in the way how you can share vendors. The first link is referring to the cross company data sharing feature which is new in Dynamics 365. The virtual company concept which was possible in AX2012 has been deprecated. For customers and vendors, you have to contact support and provide expected numbers. With too many vendors times the number of companies, it would not be honored.
Actually, the cross company data sharing is copying data to other legal entities. As mentioned, one vendor record in all legal entities is not possible anymore. A pro for the cross company data sharing is the option to exclude certain fields, so you can set local values in each legal entity, but mandatory fields must be filled. If you have different vendor groups per legal entity, you are stuck.
Via Data management, you can also copy records between legal entities. There are also ISV solutions to manage the distribution of master and reference data. E.g. within To-Increase we have MDM and data governance solutions which will offer much more flexibility and support for enriching local data and control of the master data by data stewards.
