Coursepress Pro & Multisite - Wanting to separate courses into subjects

I have a course structure that requires different subjects with many courses within each one.
It seems to be better to organise the system with each subject being its own sub-site on a multisite network.

My question is, if this is the case can students be shared across the subsites so they only need to register once and have one central place to track their progress on a subject?

Is there a better way to implement this?

This is the current structure:

> Subject 1
>>>Course1
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3
>>>Course2
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3
>>>Course3
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3

> Subject 2...
>>>Course1
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3
>>>Course2
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3
>>>Course3
>>>>>>Unit1
>>>>>>Unit2
>>>>>>Unit3