Can I rollover funds from another 529 plan into MESP?
You are permitted to transfer funds from another 529 college savings plan to an account in MESP for the same beneficiary once within a 12-month period without incurring federal income tax. The 529 college savings plan from which you are transferring funds may be subject to differences in features, costs and surrender charges. You should consult with your tax advisor or the other 529 college savings plan. Amounts transferred from another 529 college savings plan are not eligible for the Michigan income tax deduction. To do a rollover, use the Rollover Form (PDF, 56KB).
… do not insure any account or guarantee its principal or investment return except for TIAA-CREF Life Insurance Company’s guarantee to MESP under the funding agreement for the Principal Plus Interest Option. Account value will fluctuate based upon a number of factors, including general market conditions … http://www.misaves.