What is the retirement treatment of American immigrant parents?

You can buy them medical insurance, but you can't enjoy free benefits. That's for low-income people. When your parents immigrated, you were the guarantor, and the purpose of the guarantee was not to make them a burden to the US government. As a result, you apply for the benefits as soon as they come, and ultimately you pay for them yourself. Because you are the guarantor, you are responsible for the guarantee. If there is a joint guarantee, it is the responsibility of the co-sponsors.