Multiple tlt models combine

Is there any way to combine two models? Lets say i have trained using TLT for person detection and i have another model which detects face, can i combine these two into one model? Since training the model again would take time if i want both person and face.
And next time if i want person and car detection, then again i have to do training.

I am afraid not. Please train a new model if you want to detect both person and face.