Well, I'm partial to the theory that like all wild animals, the juveniles know to freeze when danger is about. I'm sure others have had this experience, but my dog (a lab with all natural instincts lost to domestication) and I walked w/in 2 feet of a fawn that just stayed hunkered down in the tall grass.
The magic database tells us the following:
Out of 960 encounters, 43 (credible) encounters involve a juvenile or infant bigfoot.
Only once was an obvious infant encountered; when it was it was accompanied by an adult.
In nineteen encounters, juveniles are spotted in the company of adults. In these cases, the presumed young range in height from 3 to 5-6 feet. And while I haven't looked them all up for this post, I'm pretty sure that in all of them, the young bigfoot is walking on its own - i.e., not being carried, or clinging to the back, like an infant would be.
Twenty-three times, presumed juveniles are encountered on their own, or at least without a visible adult nearby. Where height is reported, they range in height from 3 feet (your typical tow-headed kid?) to 6-7 feet (teenagers?).
So - have the babies and the nursery well off the beaten track, stay very quiet and reclusive while you have an infant, then start going into "normal" mode once the infants reach the age/size where they're semi-capable?