so here's my invitation question.
I am inviting a household with 3 adults and 1 child. Two of the adults are in a relationship but not married and they are providing housing, food etc. for the other two people living there (younger brothers). The older of the two younger brothers is like 23 and contributes somewhat to the household but extremely little.
The only reason I bring up who contributes what is because the eldest brother is pretty much taking care of the younger two. So, I thought maybe it's kind of a dependant situation. Can I just send 1 invitation? Is it really THAT bad of an etiquette faux pas? FWIW they're the last people I'd think of to even know that adults are supposed to have their own invite...