[Answer]-Tastypie : model has an empty attribute – reverse relationship

Now have this working by using a related_name on the ForeignKey that matches the attribute in the ToManyField:

featurelocs = fields.ToManyField('api.BFeaturelocResource2', 'fl_feature', full=True)

and

feature = fields.ForeignKey(BFeatureResource, 'feature', related_name='fl_feature')