It is possible to add a default financial Dimension for Local COA for example on the customer groups, but the same feature is not available on the vendor groups. based on the vendor group selected a default Local Coa can be added when a new vendor is created, ideal it you should be an option to make it Fixed as well so the user can not override it.
Ideas Administrator

We are pleased to announce that this idea was implemented and released in 10.0.28