Interesting link. Thanks for posting it. You say "they have to prove", but remember, they only have to prove it to a judge with a "preponderance of evidence". Any judge that grants the initial forfeiture will have already reviewed the evidence and will have already agreed that they proved it. To contest it, the family will need to file a motion with the court. The judge reviewing the motion would have to disagree with the first judge and overrule the first ruling.
I'm not saying it's impossible, but the deck is stacked against the family here. Here is some language from the link you provided:
(c)Burden of Proof.In a suit or action brought under any civil forfeiture statute for the civil forfeiture of any property
(1) the burden of proof is on the Government to establish, by a preponderance of the evidence, that the property is subject to forfeiture;
(2) the Government may use evidence gathered after the filing of a complaint for forfeiture to establish, by a preponderance of the evidence, that property is subject to forfeiture; and
(3) if the Governments theory of forfeiture is that the property was used to commit or facilitate the commission of a criminal offense, or was involved in the commission of a criminal offense, the Government shall establish that there was a substantial connection between the property and the offense.
Number (3) states that the property was "used to commit or facilitate...". The property doesn't even need to be purchased with drug money. JMO