We?re starting a project to add an individual login account to PnP for each of the tenants at an estate, so they?ll be able to access their own consumption and provisional billing data, etc.

We want to bulk create the roles and login accounts for each user. The webservices.jsp document doesn?t give example text for several of the fields required to create roles, and it looks like there may be fields missing from the login account section.

Do you have examples of the information to be included in the various fields and a more complete description of the login account requirements?

Basically, the way it works is that we submit the Add New HTML form for the entity class (same HTML page as when you say Add New and select the entity class and select all dependencies first).
We do this for every line in the spreadsheet.
So, to get a full list of variables to submit, look at the HTML source code of the Add screen, and search all INPUT fields, including the SELECT fields, to see all the column names to submit. The column name corresponds to the 'name' of the input field.
So, actually, it could be more a case of the Add screens needing to change, for you to be able to easily do what you want to do. It might be that they can already do what you want, but then again, maybe not. The Add screens generally have less functionality than the subsequent Edit screens.
I've had the idea to create 'templates' for Roles, for instance, to make it easier to create a role specially for a tenant that can only see his own meter account. In this case, what you would do, is to select the template and then the meter account on the Add Role screen, and then it would create the role accordingly. But I suppose you should already be able to do this in an upload? All you need to do is restrict Interfaces, Entities and Add, and then activate the relevant interfaces and the proper Meter Account's entity id.
So, you should actually be able to use the current Add dialogs to do what you want to do?