Are Forms Constantly Being Created?

Question:  Would Plato argue that even objects that do not exist yet, or have yet to be created, also have a certain Form?

In regard to my question, I am still not sure what Plato's opinion would be. However, there are a couple of different arguments people could make in regard to what Plato's opinion would be. One could argue that in Plato's opinion, every new object that is created is just a variation of a Form that already existed. For example, a car would be a variation of a horse and carriage. 

Someone else could argue that in Plato's opinion, a new Form is created every time a new object is created. This would mean that there is one Form for cars, and one Form for horse and carriages. However, this leads me to form a new question:  Couldn't cars and horse and carriages fall under the same Form, which includes all types of modes of transportation? But then this would mean that motorcycles and bicycles would be in the same Form as cars and horse and carriages. Essentially, I would like to know how specific Plato's Forms are. All in all, I am very undecided about my question, and am therefore very interested in other opinions.