Another thought here though...I figure there will typically be 0 or 1 assoc from a tenant record to a VerificationExpectedDatum record, correct?  So the verification biz logic will want to perform a retrieve by tenant-id to get the expected data, returning false if none is found. So perhaps a 'find_by_keystone_id(...)' call like in line 466 is needed too? 
We should probably also add a uniqueness constraint on the tenant_id column. The soft-delete feature should probably never be used on this table I'd think so that shouldn't be an issue for the uniqueness constraint. In which case the 'deleted=False' filter is not needed above.