When does the alternate medical POA get a say so?

Preventing or determining who visits is not one of the duties of a Medical POA. Doing so might be seen as isolating your mother which is a form of elder abuse.

Missing a phone call is not a reason for the alternate to take charge.

Depends how it is written. Me personally I am not in favor of more than 1 being in charge.

Normally the second in line steps in if the 1st one becomes unable to continue handling the responsibility.

Many family relationships have been destroyed due to in-house fighting over MPOA's, DPOA's and so forth.

How is the MPOA written? Both people serve together or the alternate only serves if the primary can no longer carry out their responsibilities. And, if the primary can no longer handle the responsibilities I think for the alternate to take over they need to have the primary's responsibility revoked and the alternates invoked. Its not automatic.

Some POAs are written so that more than one person has the authority to act at the same time (jointly and severally), but going by the post on this forum that doesn't seem to be a common choice. If medical POA (health care proxy) is not available and there is an urgent need there is hierarchy that is commonly followed, for financial matters it is unlikely there would ever be that degree of urgency.

The alternative DOES NOT SERVE unless and until the primary POA is UNABLE to do his or her duties or RESIGNS his or her duties.
As you can imagine, anything else would be terribly confusing.

Now, were an MD to REQUIRE a health care decision, call the primary, and the primary's husband answered and said "Golly, she just died" then the MD may ask "Do you have the phone number of the alternate POA", and may call that person.

Look up the laws for MPOA for your State and google it in this way:
"Under what circumstances does an alternate MPOA serve in the state of __________."
If this is emergent, discuss with the doctor caring for your loved one.

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