Three of them are the owner of the property but ownership percentage is based on how much they will share on the loan.
The old daddy should be $1.07M $40K = $1.11M The % ownership=1.11/2.35 = 47%
The son % of ownership on the property = 26.5%
The girl % of ownership on the property = 26.5%
The market price of property is $4M
The old daddy can get $1.88M
The son can get $1.06M
The girl can get $1.06M
The amount is still owed by the girl on the mortgage is ($2.35M x 26.5%)
$622,750 - (The amount the girl paid the loan eg. $100,000) = $522,750
The girl's ownership on the property sold to the farther and son
The amount can be get back = $(1.06M - 522,750) = $$537,250.00
The girl want $400,000 back. I think it is okay if it is based on the percentage
of ownership of the property that she need to pay the mortgage.