My mother did this and my brother joined to make a double ring, whatever ceremony. I read that for catholics to take on a minister/protestant is excommunication. Then a Bishop is needed for confession.
So, my mother, a widow, wanted to marry a divorced no religion man. So, my mother asked a new order priest, how to go abut it. (Rigid) The New Order not priest told my mom to marry by a protestant minister. Then he said, have her new husband take instructions for baptism and my mom was to go to confession. That is rigid. Her sister-in-law, of a protestant sect, arranged for ceremony to take place in her home. (The protestant minister was not about to do it in his church!) Then my brother, not thinking, decided to join in. And me, I was still new order (1987) and congratulated my mom. Ten years later, I told my mom that I know better now, that the marriage was mortal sin for her. She pretty much told me to mind my own business. Come to find out, a few women of the church shunned my mom.