Negative examples and false positives in object detection using SSD model

I am training a model to detect some objects. I have 8 classes and there are other similar objects that I don’t want the model to detect. I have tried to make an unknown class for them but they are so many and there are no pattern for the model to recognize.

How can I provide a negative examples for the model? Since that tfrecord can’t accept images without annotation and making a new class doesn’t work very well.