G.L.
If you are breastfeeding, leaving baby behind is not really an option. How disruptive would it be to take him/her with you? If the baby is under 6 months, he or she won't be crawling yet, and will be very portable. Baby can nap in the backpack or sling while you do things with the older ones. It does mean dealing with diapers, but it also means that you can feed the baby any time or place, and baby can sleep with you, so no extra bed is required. My daughter was born overseas, and we traveled a great deal with her in her infancy. It was actually much easier taking her with us before she was a year old.