Does a company buying my employer have to honor our current employment agreement under IL employment and contract laws

Small Company buyouts: I work for a very small doctor office and have for 3 years. Each year we sign a contract with the doctor that outlines our schedules, benefits, pay etc. Recently the doctor began negotiations to sell her practice to a hospital. Under the agreement work is to continue as normal etc, however I was notified that I would not be eligible to receive benefits until i worked for the hospital for 1 year. Basically the only visible change is that our paychecks will come from a new company.

Is the new company incorrect in their thinking that they don't have to roll over my time in service years?

Does the new company have to honor the existing contracts within our office? - Is this your question? Add additional information