@phdstudent
I have never prepared a Michigan return, but from my reading of the instructions, you would check both the resident and non-resident boxes and then use the worksheet.
By contacting a specialist, I meant calling turbotax customer support. They only provide limited tax advice (unless you enroll in the Live or Full Service product during tax season) but they should be able to tell you how to use the functions of the program. Not every operator knows every state, but if you call and ask for a Michigan specialist, they may be able to walk you through the process of entering the data and allocating your income.
https://ttlc.intuit.com/turbotax-support/en-us/contact
