Addressing Invites?

Knottie1429926455

Two questions:

My future father in law goes by his middle name (his son shares his name, as does his own father). When addressing invites, do I need to use his given first name or would it be appropriate to call him by his middle name?

2nd: I've always hated the archaic feel of addressing things as "Mr. and Mrs. His Name"
How do you stylize it when using both names "Mr. Joe and Mrs. Jane Last Name" or "Mr. Joe Last Name and Mrs. Jane Last Name"

CMGragain

Does his father share his entire name?  Does his son?  Is Grandpa still living?
If all three men are living and have the identical name, then they are Mr. John George Doe, senior,  Mr. John George Doe, junior,  and Mr. John George Doe, III.
If the middle name varies, then just use the entire name, Mr. and Mrs. John George Doe., Mr. and Mrs. John Frederick Doe, etc.