The recent TV Guide Q&A (mild spoilers) confirms that Jack Coleman is awesome:
It's kind of weird that two single straight guys, Mohinder and Matt, are in charge of little Molly. Is this arrangement legal?
"In reality, no one has talked about adoption or legal custody," admits Loeb. "The opportunity to do our version of My Two Dads was too delightful to deal with details." Actor Jack Coleman (HRG) also weighed in here, noting that this isn't the first no-hassle kiddie custody on Heroes. "There's nothing official about HRG's adoption of Claire," he says. "Kaito [George Takei] simply handed her to me on a roof. We're not really concerned much with legalities on Heroes, you know. We take liberties with reality. Here's another spoiler: People can't fly."