A "recourse" loan is one in which the creditor can go after you personally for the balance. For instance first mortages are generally non-recourse loans, after the lender takes the house, they cannot pursue the borrower for the rest of the money.
Student loans are the ultimate recourse loan not written by actual mafia, because student loans ignore bankruptcy and statutes of limitations, and can chase you for the rest of your life.
If the second mortgage is a recourse loan, your parents can escape it by filing bankruptcy, or functional equivalents. If it's non-recourse, it's even easier - just walk away from the house and your student loans are gone (in exchange for some marks on their credit report).
Either way, this is a big upgrade from that nasty student loan, if we consider your family as a single unit. If we do not, then it's an even bigger upgrade, because problems in this loan won't even show up on your credit report, to be dreadfully mercenary about it.
Realistically, this is the weak spot here. Effectively you have borrowed money from your parents and put them in a heck of a spot. You need to cover that 2nd mortgage, or they take the credit hit and they lose their house.
On the other hand, they may be able to tax-deduct their 2nd mortgage interest, and so you may want to arrange something to have this passed back to you. This makes the interest rate more favorable.
The #1 thing that goes wrong in this scenario is you stop paying and they don't know you stopped paying. Typically (like cosigner situations) the first they hear of it is a bad mark on their credit report -- because unbeknownst to them, the situation went 30, 60 days past due. If only the other person had known, they could have easily made the payment as they did promise to do, and avoided the needless consequences.
So I would change the "pipelining" of how these payments are paid. I would have you pay your parents, and have the parents pay the mortgage. That way they are intimately aware that the payment is being made, since they are making it.
If you make this routine and normal now, that will completely avoid the awkwardness and humiliation later to man up to tell them timely that you will be unable to make the next payment, or the relationship-breaking cowardice of failing to do so. Further, if you do their part and they fail; the consequences fall on them where it belongs.
401Ks, IRAs and the like
None of this is any reason not to max out your 401K and do a non-deductible IRA to boot.
I don't mean "to the employer match"; that's waving a banana in front of a monkey. It's a sad state of affairs that we must resort so such cheap chicanery to get people to do the smart thing that would be obvious if they had any financial education at all. The whole point of the match is to get people to start thinking about what retirement saving actually is, on the hopes that they start to grok "Wow, this is the best deal in the history of money, and will make a huge difference in my elder life!"
I found myself on a Board managing an endowment: a "forever" chunk of capital where the university's program is funded by the appreciation. These are tightly regulated, and there's a "gold standard" for how they MUST be invested - heavily in equities where the growth is (and the volatility, but you don't care about that on a long term investment). Correctly done, you double your capital every 7 years on average, over the long term. You're making 10, 11% effective interest.
At 24yo, your 401K/IRA gets invested likewise. The needed funds are available in your 401K.
Everybody has something better to do with the money today. But if you wait til age 31 you'll only have half the money for retirement. If you wait til age 38, 1/4 the money. This multiplying power (of compounding) makes it very urgent you max out the 401Ks today, and then, also max out a non-deductible IRA (and immediately convert to Roth, since this is free to do). If you contributed the max from age 24-33, then stopped, you'd be better off than if you started contributing the max at age 34 and continued until retirement. And I'm sure $20k/year extra in mid-career would be helpful, sure beats playing "catch-up" on retirement because you started too late. Struggle a little now, take big payoffs later.
Relating to student loans, I recommend maxing retirement first, because it grows faster than the student loan interest costs. But still at your salary you should be able to knock both out.
I'm sorry to beat the drum so hard, but investing for retirement early is so ridiculously overpowered when you are young. Take full advantage of it!
And never, never, never cash out a 401K early. They are fully protected from lawsuit and bankruptcy. In some states, IRAs enjoy the same protection. Life will be full of emergencies that seem fixable with a big shot of cash. It always seems that way and is rarely true. The power to resist throwing money at every problem is an important wealth skill.