Out of three children does the one who wants to be guardian have to have approval from the other two?

If the court appoints the Guardian, in most states the court requires the Guardian to file regular Accountings with the Court that includes bank statements, checks, receipts, invoices, etc. that shows where every penny is spent. So, whoever handles the finances, is under tight scrutiny. The Court reviews it to ensure the money is spent only on the Ward in a proper way.

Medical POA normally does not allow one to handle financial matters. And regardless of who is appointed POA, if there is a Petition to appoint a Guardian, the appointed POA is not necessarily recognized. The court may appoint someone who is not the POA.

My sister has medical poa and refuses to share any issues. Now she wants to handle his finances.

I have this situation exactly, however, my bro tells my dad dont to expect 'drop in' visits like he gets at the assissted living home - because he's got an issue with me is obvious. so now I am faced with prospect of moving or being the one to tell my 94year old italian father he shouldnt move into a home served by strangers. (help)

All siblings are served notice of the court hearing, a "show cause" where they are entitled to have their say. Certainly the Judge wants to hear from all sides. The court evaluator will also try to contact them and get their opinion.

I think so, and sibling(s) can object.

You will need an attorney. If there is conflict among the children the court has the option of appointing a third-party to the guardianship role.

I would consult with an attorney. In most states the Court appoints the Guardian and they review all evidence to see who is most qualified and willing to serve.