Just a heads up, many unrelated OP's use the same doctor as well. The docs are independent and simply take a cut up front, they don't affiliate with any specific entity in most cases.
I guess one could technically say that using the same doc DRAWS a relationship between OP's, but the OP's themselves are still not related by any other means. There are exceptions, but by and large the doctor is no indication of anything other than business relationships and nothing more.
That won't stop the doc from remembering someone from an unrelated OP with which he/she works though......