The trustee of a living trust is the person who invests, manages and distributes the trust property, according to the trust agreement or verbal instructions from the trust's creator. A living trust may be large enough to require more than one trustee, or co-trustees. The current trustee can only add another trustee if the trust agreement allows the trustee to do so.
Review the trust agreement to determine whether it provides authority for adding a co-trustee. If the trust creator did not create a written trust agreement, or if the trust agreement does not mention whether a co-trustee is or is not acceptable, then the current trustee generally has discretion to make that decision. But if the irrevocable trust agreement expressly prohibits the current trustee from adding a co-trustee then the trustee and beneficiaries, or a judge, will have to agree to amend the trust before adding a co-trustee.
Amend the trust agreement if it does not currently provide authority to add a co-trustee.
Identify the new co-trustee in the written trust agreement. You can do this by amending and restating the trust agreement in whole, or by simply attaching a rider or exhibit to the trust agreement that identifies the new co-trustee.
Transfer appropriate property held by the trust to the co-trustee. Either or both trustees can own any property held by the trust. Both trustees will own the trust property subject to the terms, conditions and restrictions of the trust agreement.
Notify all interested parties of the appointment of the new co-trustee. Interested parties include the trust's creator, the current trustee and any beneficiaries of the trust. Interested parties also include any financial or insurance companies that name the trustee, or the trust, as a beneficiary on an account or policy.