@brucer815 We ended up using the WCFM Membership registration form, accessed by selecting a membership from the membership table created by the plugin.
Thanks. We do require the Multivendor Membership plugin, but we worked around this issue by disabling the WooCommerce registration form on the My Account page, and instead adding in the Dokan vendor registration form.
That took care of it. Thanks. I would humbly suggest that feature as a request for a future version, but the PHP API client solved my immediate problem.