Help with Addressing Invitations / STDs

erinmmcd

I've gone through 117 family address groupings trying to write out how I will address each invitation for A) save the dates (which I know I'm behind on) and the invitations.  Right now I'm assuming STDs and formal invites will be addressed the same.

• Do you write Mr. and Mrs.  or   Mr. & Mrs.  ?
• Ms. versus Miss (is this age dependent?)
• Mr. versus Master (when the heck do you use Master?)
• Is it Mrs. or Ms. if the woman is married, but kept her last name?

Okay, and then here are the situational addressing problems:

• Parents + some Adult children living at home (not the whole family):
  Mr. and Mrs. First Last
  Mr. Michael and/& Ms. Catherine Last NameFollow up question to that one: for adult children, does age or gender go first (little brother, older sister in this case)

 Parents + little kids (whole family)
Mr. and Mrs. First Last
and Family
OR
Mr. and Mrs. First Last
Mr. Sean and/& Ms. Catherine Last Name

• Parents + 3 little girls
  Mr. and Mrs. First Last
  and Family
  OR
  Mr. and Mrs. First Last
  Ms. Tessa, Ms. Lily, and Ms. Maggie Last Name
  OR
  something else?? ("Misses?")
  
  

• Parents + 3 adult sons living at home + one of the sons gets a guest (long term gf/fiance situation)
  
  Mr. and Mrs. First Last
  and Family
  OR
  Mr. and Mrs. First Last
  Mr. Son1, Mr. Son2, and Mr. Son3 Last Name and Guest
  OR
  something else?? ("Misters?")
  

• Parents + 4 late teen/adult kids at home + one kid has a toddler
  Mr. and Mrs. First Last
  and Family
  OR
  Mr. and Mrs. First Last
  Mr. Son1, Mr. Son2, and Ms. Daughter1, Ms. Daughter2, and Toddler Last Name
  OR
  something else??

I've thought about just creating separate invites for the son + guest and for the daughter + toddler (but feel weird sending multiple invitations to the same address).

TIA for the help!