My recently deceased mother used to say:"If you let yourself be a doormat, people WILL wipe their feet on you." IOW, you cannot be taken advantage of unless you let yourself be taken advantage of.

They sound like a couple of characters out of a Jane Austen novel!

Don't invite the moochers. If they show up uninvited, say "Sorry, we already have company" or "Sorry, but we have something to take care of that's a family matter."