Predictions

Mir Khan ran away with the child for some personal revenge (not for monetary reasons), he seems like a really twisted guy (base don the way he spoke to Zain), so he might have sent back Barkat's bloodied clothes to make Suraiya and Usmaan feel like he had killed their daughter, (hence Suraiya's reaction), we know Barkat is alive as per IF article, so maybe usmaan and Suraiya got some clue of her being alive. The well is probably where Mir left all of the girl's stuff or maybe the place she was initially hidden before Mir took her away again was in that well, when they found out they were devastated and closed off that area and placed all her stuff there.