glatt

Question

I read a teshuva that if you are invited to an eshkenaz friend or wedding and they do not normally keep glatt you can eat based on safek sefeka (safek if the piece of meat you are eating came from a cow with a sircha that was removed, and safek if the halacha is like the rama). a)does your father agree to this? b)if so, can you go to a non-glatt restaurant and rely on this safek sefeka. or is the heter only because you were invited and not to embarrass them.