i know its so stressful, the olders bring home every disgusting thing from school. just do what you are doing, lots of hand washing, everyone washes every time they come into the house, and open your windows. shoes off at the door. backpacks and coats and clothes from school get their own spot, not on the kitchen table, and change out of school clothes and wash up asap. separate towels for sickies and not, better yet no hand towels at all, put a roll of paper towels in the bathrooms. antibacterial soap when things are especially germy. extra vitamins. antibacterial wipes in there with the school kids lunch. and when your newborn is sick, bring her in to the doc as often as you need to. at least call in for any fever. i was on the phone with my doc constantly. if they make you feel bad about calling you might want to rethink your choice of doc, you should be able to call any time, especially with a newborn. ask your doc if they have newborn hours, mine used to let me bring them in the back door to minimize exposure. if not, try to go first thing in the morning or first thing after their lunch break, the office will air out a bit and be cleaned. the baby will get sick anyway here and there, just do the best you can. the baby will build up immunities sooner than the others, thats what i kept telling myself. made me feel a little better, but we always worry.