Well, you don't necessarily need to post everything,but it would be helpful to have names, relationships, birthdates, spouses, and info on where in the US they lived, were born, etc.
For instance, are Mary, Frank, John and Catherine siblings? Cousins? Where did they live in the US, and when?
If we can find them in a census, that should give us a country of origin for them and their parents, and some idea of when they emigrated.
If Frank and John were born in Europe, a US draft registration might give the name of the village where they were born and their exact birthdate.
But in order to find these type of records, we have to know their approximate birthdates (give or take a couple years) and where they lived in the US during census years (1900, 1910, 1920, 1930,1940 (not necessarily every one of these years, but at least one)).