Legal Question in Real Estate Law in Illinois

Even without a lease, there is a tenancy, most likely month to month. As far as kicking you out, they can ask, but they should not take any action to physically remove you or your belongings without a court order.

I agree with Mr. Repay that she can not without a court order, but I have a question as to who the real tenant is because your statement of the situation is confusing. I can't tell if your grandmother is the real tenant or not: just because she pays the rent doesn't make her the tenant. And if she is the tenant then you, your dad and his girlfriend could be your grandmother's subtenants. And then the three of you are like "partners" and without a partnership agreement your dad's girlfriend would have no say-so on her own to take any action against you, and only your grandmother might have the "jurisdiction" to evict you. If your grandmother is NOT the real tenant, the outcome could be different. So it might be worth your while to clarify this if you can.