anyone can put a mechanic lien on your property, without any cause, but they must follow up with a judgement to make it valid.
so, if these subs don't get pay, yes they can and will put a lien on your house, but to valid that, they must sue you and win.
you need to show the court your original contact and its pay in full, you shouldn't have any problem, after that, you can request to remove the lien.
in Indiana, they have up to one year to file the lawsuit, but i suggest you get an attorney at this point, you can do a we call the sue or drop, have your attorney send them a letter, tell them if they don't bring suit within certain time, like 30 days, you can counter sue to have it drop.
if they win, they be in junior lien, they can foreclose on you, but they must buy out the first lien first, which be your mortgage.
if they are threaten you, call the cops.