I rather doubt they were told that they were also signing their children into servitude. Did you read the link?
You did know Schoharie burned down and we lost most of the detailed records so a lot of what is "known" today is actually speculation!
The Herkemir Militia ~ keep your eyes on that body ~ and BTW, the writer of that link assumed the nearby "friendly Indians" were Mohawk ~ I think he got the tribe wrong since they were Oneida and Canandaigua. The Mohawk, in the end, were not so friendly.
Regarding the Indians, the family Bibles refer to “the Mohawk Indians” but that’s gotta’ be a reference to the Indians then living ALONG THE MOHAWK RIVER ~ which runs through the area. The actual Indians in the vicinity are the Oneida and Canandaigua, not the Mohawk.