While a guardianship and a POA are not identical, they are similar; and, if anything, a guardianship is broader than a POA, since as legal guardian, you have the power to make all decisions for him (over his finances and medical care) that a person could normally make over himself. The home should be including you in all decisions; if they are not, you could bring a legal action in chancery court (a part or division of county court) for a court order requiring them to include you. Such an action can be procedurally complex; you should retain an attorney to help you if possible.