Did you consider equity or investment from a source outside of the deal who would be willing to “gift “you some funds?

@Sean PeabodyDSCR loans are likely the easiest way to go about this if the property is already rented and cash flows.

And they could gift it back to you using normal annual limits. 

There are 2 issues at play. 1) The buyer and 2) the appraiser.I'll focus mostly on number 2.If it's below grade, an appraiser is not going to include it in gross living area, and they aren't going to call it a bedroom, an ADU, or any of that (in the unlikely event that they do, you got lucky with a very liberal appraiser who gave you a gift, I'd suggest shutting up and not questioning it, hopefully the mortgage underwriter is having an "off" day and doesn't notice, but you certainly don't want to bring attention to it!).

So he’s basically gifting you 50%.

easiest way is to just pay them a rate of return. for 5k each i wouldnt be giving up any equity if i didnt have to. run the numbers and see what you can afford to pay them in interest.just a thought, may be worth looking into hard money. if youre looking for something that needs work, i know my guy will do 100% of rehab. if you are raising just enough to get into the deal, you do not want to go into the rehab having spent all your money. happy to share more thoughts.

First, if it were me, I would probably move and rent the whole place out as one unit(maybe make the basement a second unit if it has a separate entry. to be honest, this may not be the best way but it is the fastest and easiest way to get it rented.  

Not the fastest and most financially beneficial but the easiest way to get started and ease your way into it.1.

Once we finally found the right deal and saw how favorably the numbers penciled out, raising equity was the easiest part of the process.4.)

@Juan Martinezmight be best to go hard money/investor loan. with conventional financing, if you owe your dad back they will count that against you. you would need to get him to sign something that it is a gift and does not need to be repaid if you do not want it to count against you. with hard money, there is far less nit picking around stuff like that. i always lean hard money if there is a way to create value in property. happy to share more info if you want.