The only way to keep the existing 1st is to find a private lender/partner that will take a 2nd.   

Send me a private message to connect with your email and I can get you connected with the owner through an email introduction.

HML or private money to make a cash offer, maybe.What is your ultimate goal on this property? 

If you find you're unable to get something right away due to your credit or income situation, you may still be able to acquire your first place creatively via a lease/option, seller financing or buying a place 'subject-to' the existing financing, plus there's always hard or private money however either of the last two would require having 'take-out' financing lined up in advance, which might be a stumbling block.

If you want suggestions, contact me via private message.

Outside of portfolio loans (great option), here are a couple other options for growth:Raise private money to purchase dealsPay down the mortgage on one property with the snowball method.

I compare my services to those of the "competition" and the private Landlord: online payments, solid screening, no evictions in 5 years, over 340 rentals under management, member of NARPM and higher code of ethics, etc.3.

Or are you a hard money/private money lender as well. 

I have dealt with both and @Darrin Carey is something of a hybrid between hard and private money. 

Some use Private money at less and no points, etc.