Getting a mortgage without a job will be near impossible without going with an alternative loan product that will come with a high down payment and high interest, which is not the "househacking" way. 

If you have enough funds in an IRA the alternative would be to establish a self-directed IRA, and have the IRA buy the property subject to existing financing (if your sister is willing to do that), you personally can't assume the mortgage b/c you are not allowed to provide a personal guarantee for IRA-owned property and have the IRA pay your sister for the equity.

It’s often sold as an alternative to larger security deposits or co-signers for people with bad credit bad rental history.

Make sure they are ample.Second: what are your alternative investments.

You can buy title insurance anyway, without conveying the property, so that's an alternative.

Hi Brick,As an alternative, you may want to consider converting the 4 units to 4 condos and selling each individually.

I vividly remember the countless hours spent driving to and from remote locations in rural Manitoba, alternating between early BP podcasts and Jim Rohn recordings.Over the next two years, I adopted an extremely frugal lifestyle, enabling me to achieve a 75% savings rate, sold my custom truck for a used Toyota, traded my new home in the burbs for a duplex (house-hack) in a challenging neighbourhood of Winnipeg where attempted break-ins were commonplace.

This trend suggests a growing rental market as more people are unable to afford buying homes under current economic conditions.while the housing market may face challenges, the rental market will likely expand as an alternative for those priced out of buying homes.

A few things to point out as your hear recommendations for alternative financing, i.e.

If they signed paperwork saying they'd be out, then it is up to them to be out and find alternate housing.