That's it: loose boundaries, we'll happily squint if things are implied rather than stated outright, but obviously it's an R/T comm and people are here as they like both characters. Whether that's when they're together, or before they were together, or even afterwards... That all comes under the loose boundaries!

And yes regarding Teddy. The stories (or art) only have to touch on his parents in some aspect, but then nearly all that I've read do without really trying. ;)