I buy/sell without regard to other property (except when pooling in a mortgage tranche) so can't relate directly with your scenario, but talk to your loan servicer. they can help. 

I have a duplex in Ohio where the tenants pay $1500/mo; I pay mortgage & utilities, about $800/mo.

Hey @Adriana McLaughlin - This is actually the FIRST TIME I have heard of the term "ALL-IN-ONE-FIRST-LIEN", but after doing a little bit of reading on it I am not sure I still completely understand.Basically, you apply for a HELOC credit payoff your existing mortgage with this variable HELOC and then in theory have some leftover as well...so the advantage is paying off your loan early and getting access to a line of credit, but the disadvantage would be a variable rate mortgage for the reminder due on your orginal first mortgage? 

No, if a mortgage was recorded, it would have to be paid off, or the holder of the mortgage would have to agree to an assumption, or to write a new note/mortgage with the new buyer.

I want to use the equity from the house to buy more real estate, but most lenders require my name to be on the title to prove ownership.

My mortgage payment is 800 and 1000 so when you figure in and account for the expense they basically break even.

Is that $50k net with an $850k mortgage at 7.5-8%?

It might be a lender dictate.

But otherwise you'll have too much mortgage boot to make it worth your while if you just use the cash proceeds.  

The lender will only communicate about a specific loan with the borrower.