I don’t think the owner of the first mortgage cares that much if there is additonal financing added later. First of all, they can’t do anything about it, and they’re probably not going to know about it anyway. And some, (that’s some – I’m not saying most), some people who take out second mortgages may use it for home improvement, or landscaping and pools on new houses, which may (that’s may) increase the value of the property.
