Please do not use any married names, if you do not know the maiden name then just say you don't know, and leave the name out. I would also recommend you not use any married names in your research, then it is always clear what you have and do not have for information.
Unless your mother-in-law's mother was not married she would not have the same last name as her daughter.
Metgei is that a first or last name? I think the name might be mangled a bit and it is something else.
Any more relevant information would be helpful, where was she born, was she married? To whom? When? Where? Brothers? Sisters?