Tragic.
I have flown for a long time out of Weston on the Green (D 129)and Kidlington.
Gliders and parachutists can mix - albeit on the ground at Weston we sometimes felt we played second fiddle - losing out on a launch slots etc - but always "better safe".
Pre flight briefing for Weston gliders always includes - do not go in the DZ which today is here ... infringements were occasional, most often by "strangers".
Rookie parachutists can be a hazard, landing well outside the intended area - but since they are on are static released at 2,000 or thereabouts, they are typically low and visible. The accident mentioned sounds like someone was in free fall - I wonder how high they were when they collided & presumably the glider pilot did not get a chance to jump ?. (Most glider pilots wear parachutes - unlike their powered bretheren - but getting out of a glider at high 'g' is not straightforward ...).
Basic advice is obviously - power pilots stay far away from any DZ - or only enter it when the parachutists give clearance. (Do the frequencies need to be displayed more clearly ?. Nav warning bulletins ?).
At Kidlington they are well used to Weston being active and pilots rejoining from anywhere east are quite often advised to come in via Westcott - passing well to the south of Weston.
D 129