‘ And Joshua, and all Israel with him, took Achan the son of Zerah, and the silver, and the garment, and the wedge of gold, and his sons and his daughters, and his oxen, and his asses, and his sheep and his tent, and all that he had, and they brought them to the valley of Achor.'
No one, least of all Achan, was in any doubt as to what would happen next. Their contact with the devoted thing rendered them all ‘devoted'. Note the order of descending value. The initial devoted things first, then the blood relatives, then the livestock, then his home, then everything else.
Note that ‘All Israel' were involved. This deeply affected them all. In the Hebrew ‘All Israel with him' comes at the end of the sentence. It is placed there for special emphasis to stress their involvement, a device witnessed elsewhere (e.g. Genesis 2:9). We would show this by putting it in capital letters or italics.
The sons and daughters were possibly those who knew what he had done and had connived in it. They were guilty of complicity. They may well have helped to hide the devoted items. And by hiding in his tent what was devoted he had necessarily involved them all. But even the livestock were affected. They too had become ‘devoted' by his actions. All were now YHWH's. (Interestingly no wife is mentioned. Perhaps she was dead. Or perhaps she had known nothing about the affair).
“The valley of Achor.” Possibly we should translate ‘low lying plain of Achor'. El Buqei‘a is suggested as a possibility. It would be seen as an abandoned place, a place to be avoided. Making it ‘a door of hope' later would be a sign of YHWH's love and compassion (Hosea 2:15; Isaiah 65:10).