You can't get it under contract, use a Quitclaim Deed, or access the mortgage holder.

If a junior lien holder is not notified of the sale, their lien is not wiped out.Its your call.

When you sell and you owe on the property, the title/closing company will request a payoff statement from your mortgage holder. 

In her case, she was able to contest the 2nd lien and was able to get this ruled in her favor, due to negligence of account tracking by the lien holder. 

The senior lien holder essentially sets the terms of the deal.

If your deed is subject to the rights of the (or other) lien holders then they have priority.

As a flipper, do I need to be an additional insured on the GC insurance AND listed as a “certificate holder”.

However, they have the option to pay off subsequent (newer) liens at any point and would roll the redemptive value of the subsequent lien into their lien.You can negotiate a discount with another lien holder to buy the lien (at a discount or a premium), but you cannot negotiate with the tax collector for a discount on the payoff of a lien (either as the homeowner or another lien holder).

In your case, a second mortgage holder is much more willing to negotiate, since they will likely get nothing if the first forecloses.

Why would a first mortgage holder even consider such a concession?