I can't think of any occasions when an English region opted out of Grandstand - maybe Rugby League in the Leeds area may have been the one exception, although the staffing would have had to have come from Manchester OBs.
I've got a couple of Radio Times from the late eighties where Great Britain, as was, were playing Australia in rugby league, in Australia, at about 6am, and it was only shown live in the Northern regions, the others not opening up at all. There were highlights nationwide later in the day. Of course, the Northern regions still do opt out for rugby league now.
Grandstand used to have a regional opt spot for local results at one time I believe. That got spun off into a standalone news and support bulletin.
There was a regional opt for Rugby Union in the West, South West and Midlands regions in 2005
This isn't the same, but I do remember in 2001, they were going to show an Edinburgh vs Ulster rugby match on Grandstand, and it was billed in all the TV guides, but then on the show itself they had to apologise because for contractual reasons they realised they could actually only show it in Scotland and Northern Ireland. They did show it in those nations and the network Grandstand cobbled together some replacement sport.
The local sports round-ups were after Grandstand and were what is now the Saturday teatime news, but in those days were pretty much 90% sport with just a brief round-up of news, if that. Of course, in those days the South East didn't have any regional programmes so Grandstand would come back in that region for another five minutes, billed as Today's Sport, which although it was only been shown in the South East wasn't specifically locally orientated (presumably it was handy in case any other region couldn't opt out). Des Lynam said that, despite it only lasting five minutes, it was a hundred times more complicated to do than the five-hour Grandstand they'd just done because it was just a relentless procession of graphics and photos, the presenter trying to time the script to match with it all, to the extent Des refused to do it eventually.
Steve in Pudsey gave kudos