If you subscribe to ancestry, you can just merge the census records for the whole family in one operation. Ancestry/FTM will post the facts, source, citations, and image to the Name, birth, and residence facts for each person in a household from 1880-1940. Before 1880, it will only post name, birth and residence to one person at a time. This is because US censuses before 1880 didn't show relationships.

If you don't subscribe to ancestry, it's actually more work than you describe; as you have to make a fact or add a citations fro name, birth, and residence for each person in the house. A family of five will therefore need 15 facts and 15 citations. Beginning with FTM2012 (you didn't say which version you have), you can shorten this step by right-click copying a fact and right click pasting that fact to members of that person's immediate family.

I think it may be worth your while to subscribe to ancestry for a month and get all of your census, WWI draft registrations, Civil War records, plus whatever else you find - posted in that month.