What is my inside address if it is going to more than one or two individual professionals? They are all at the same address so may I list them all with their titles in the same inside address? Is that professional?
If sending the same letter to several individuals, each should have his/her own copy, with his/her address at the top; the other recipients are listed after the signature block with a preceding abbreviation of "cc":
cc: AAA, BBB, CCC, DDD