It would depend on how the parents entered the country. If they are overstay the petition can take place within the country, just as any other petition at this moment, if they are EWI they have to leave activating the 10-year ban.

However, that is based on current laws and the version that seems to be trying to go through right now, there is no reason to expect that this version of the dream act or the immigration laws regulating family petitions will not be changed between now and a decade. The DA has not gone up for vote yet, right now its looking like an up hill battle, so its time to do our magic and really change the perception of the the people about who the dreamers really are, pleas to politicians it could be tried but I still think it falls on deaf ears unless we are somehow able to compete with the people making millions off of incarcerating more people, money talks to a lot of the politicians unfortunately, but something that could sway their vote would be the votes that ensures they stay in power.

Frankly, as 2Face mentioned, the DA IS very right now, lets make sure it gets through.