I can definitely envision a scenario under which Lilly and Jack were taken to "go live" with another family (or worse, trafficked with no promise of a loving family) far away.
IMO, it didn't have to be an opportunistic total stranger abduction or total stranger who took them to traffic them for profit.
LE/RCMP has said they don't think they were / have no evidence of them being abducted.
However, they still could have been taken with good planning to leave no trace (e.g., using burner phones, knowing cell towers to avoid using electronics near which could track a signal & that it was such a remote location it would be easier to take them than in a densely populated area) and perhaps working in collusion with someone close by or closer to them who wouldn't be as suspicious as a stranger or would be good at hiding their involvement.
They could have been lured to come outside ahead of time through the offer of something appealing like the promise of a big treat or adventure, which could have been why their parents said they were excitedly chatting in the privacy of their bedroom the night before, they slept in their clothes, Lilly had her backpack with her by the bed & may have left with it (a secret message slipped to her on where to meet & when), and most importantly IMO, them leaving quietly, IIRC.
If they were taken, the person(s) could have been lving or operating within the outer circles of their community or families, someone with known or peripheral connections to them or even some time random access to them, who had their own motives.
They could have been either deluded they would be acting in their best interest/arranging a place for them to be taken care of if there was neglect or abuse and/or to benefit financially.
So could have been someone who knew them or knew of them & perhaps also needed money & thought they all would be better off....
And they could have heard through the grapevine of or knew someone who worked the trafficking circuit & could get them far away quickly & were experienced at how to keep it all under wraps regardless of pressure/an intense investigation & rewards by LE.
IIRC, it was well over a week after searching for them close to home and having wandered before RCMP said they were shifting the focus of their investigation outward into the community, region, other regions, etc. By then, if they were taken and moved quickly via trafficking networks of any stripe, which are known to be operating in their region, they & the perps & any intelligence besides road, toll or bridge cameras would have been long gone. And traffickers know how to move people without being recorded, IMO.
JMO, trafficking is not off the list if they were handed over to the pros by someone(s) who had inside knowledge of their circumstances & schedule that week not attending school & thought they could make it look like it did at first, that they wandered, while they were being transported far away by well disguised perps, colluders, vehicle(s) and savvy traffickers.
JMO