A guardian, without authorization of the Court, may not revoke a health care proxy of which the incapacitated person is the principal. If a health care proxy is in effect, absent an order of the Court to the contrary, a healthcare decision of the agent takes precedence over that of a guardian. 5309(e)
On the other hand, a DPOA agent is accountable to a conservator and the conservator has power to revoke or amend the DPOA. 5-503
A person nominated in a DPOA (but not a HCP) has priority for appointment as guardian or conservator. 5305(b), 5409(a) (1). G.L. c. 201B, §3. A nomination in a DPOA may include a request that the guardian and/or conservator bond be without sureties.