Answer:
The grantor's SSN can still be used as long as the trust is still revocable. Generally, a grantor trust becomes irrevocable upon the death of a grantor. Then, an EIN is required.
Changing trustees does not change ownership.
The grantor's SSN can still be used as long as the trust is still revocable. Generally, a grantor trust becomes irrevocable upon the death of a grantor. Then, an EIN is required.
Changing trustees does not change ownership.