Flood - mortgagee endorsement for 2nd lien positi

We acquired a land only loan. There is a 1st mortgagee before us with a lien on the mobile home. Our acquired Deed of Trust does not have any language that would include existing or subsequently erected or affixed building, improvements and fixtures. My question: The flood coverage on this loan includes us as 2nd mortgagee. We have no security interest in the structure. This doesn't seem to be necessary or required. Isn't the coverage necessary for the 1st lien holder only? Shouldn't we cancel our mortgagee endorsement and take the policy off of our tickler system?

Has the mobile home been converted to part of the real property? How does the first mortgagee have a lien on the mobile home?