Grandparents don't have to socially distance now? Confused

It’s obvious that as there is no longer any key worker childcare that many grandparents will have no option but to step in and fill the gap. This has happened in my family. One grandchild is still cared for by his parents as one works mainly from home (only one meeting in London since lockdown) and the other parent was made redundant, so at home all the time now. However, my daughter and her husband are key workers and have three young children. The youngest still goes to his nursery, but the six year old twins would have no childcare if we had not filled the gap for three days a week. The guidance on childcare is not law. It is guidance. The government cannot expect key workers to go to work, and others to return to work, if there is no childcare in place. Consequently grandparents have had little choice but to step up to the mark. Presumably that’s why the question of grandparents and grandchildren is guidance not law. I don’t suppose the government want grandparents being prosecuted for taking care of grandchildren. Imagine the headlines