Unless the APS worker is a lawyer he/she shouldn't be giving legal advice. Even if they are a lawyer, your parent and sibling are not their client. That said, your father's Will doesn't take effect until he is dead and it is probated. To avoid costly mistakes your sibling with the POA needs to consult with an elder law attorney.
I agree with Mr. Davis. I would just suggest another possibility. It seems to me that if the deeds were changed, the APS worker may be suggesting that the changes were not proper and should be undone. It is possible that your brother may have acted in a way that would breach his fiduciary duties. This, of course, depends on what was done.
Your brother needs to consult with an attorney. You may need to do so, as well.
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The last will governs as both were competent. Your brother should consider your fathers last competent wishes. The power of attorney must be durable to apply during incompetency. Changing deeds while he is alive could make the transfers easier. I'd consult with elder care attorney how to do this, not a social worker