Marriage certificate for Germany visa?

Okay, not an opinion question but a factual one. Do one need a marriage certificate to claim Germany visa? The person is from India, Bangladesh, SriLanka

Someone I knew who dated for 3+ years married his boyfriend and now they are going to Germany. Her parents said they needed a marriage certificate. I'm not quite sure because our friends had went to Germany, they are not married though. Plus, they are just college graduates. I mean it could be truth. I just don't know for sure maybe that's why I'm here asking...

Marriage certificate for Germany visa?
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