@Jessica Soares
No, I have not used HML, but I'm sure you can find a few people on this forum that have used them successfully. There is also at least one podcast dealing with the subject. I agree that it seems intimidating, but I think if I had a good deal with more than one exit strategy I'd give it a shot.
As far as keeping current financing in place, the specifics would have to be worked out with the owner, but some may be willing to take a small amount of cash upfront in exchange for you getting payments current (if behind) and paying off the balance when you sell the property.
This can also be intimidating because of DOS clauses, but I've seen quite a few people say that they do these deals frequently without having the loans called.
I'm not an expert on any of this, just some things I know a little about that sound like they might work for your situation. As always, do some reading and consult with experts. Learning new ways to do business is one of the things that interests/excites me most about REI.