We train the network using mini-batches of data (if you want to change the size of the mini-batches they can do that in trainingOptions).
If this is what you are following and what you are asking is if you can retrain on multiple datasets, then the answer is yes. You can follow the same workflow for transfer learning that is mentioned in the documentation. Take the trained network, get the layerGraph(net), modify layer graph if needed, and then retrain using trainNetwork and the new dataset.
Please follow the below links for more reference:
Hope this helps!
