addressing question

My sis and BIL are drs. On the std I put Mr and Mrs but obviously that's wrong. How do you address the envelope?

Drs Robert Smith

Dr Robert & Dr Sally Smith

Help!

Q&A: Invitations: Addressing One to Doctors?
Q.How do you address an invitation to a doctor?

A.

If a wife and husband are both doctors, the outer and inner envelopes should be addressed to: 'The Doctors Rosenthal.' It's that simple! If they're married but have different last names, list both names in alphabetical order on separate lines: 'Dr. Rosenthal' followed by 'Dr. Schwartz'.

If only one spouse is a doctor, list the person with the professional name first: 'Dr. Kate Randolph Mr. Brian Randolph' or 'Dr. Kate Randolph and Mr. Brian Randolph' (if it fits on one line).