The question I have is whether "poder" is simply about possibility, or whether it also covers prohibition.
Examples: If the living room has just been sprayed with a powerful insect repellent, then it would not be advisable that someone plays there. In that case the English translation is good enough. OTOH if I don't want playing children to knock over valuable Chinese vases, then my English translation would be "must not." Would that also be "no pueden" in Spanish?