So, our group (of which I'm the DM) was in a situation in which they wanted to drag each other during their turns (roughly an equivalent in increase of speed to the Dash action, as I pointed out) to escape a monster (well, a group of kobolds).
So, as to 'dragging' the others, they wanted to do something like grappling, but no skill checks or anything, just halving movement speed and dragging them. They took turns doing this and outpaced the kobolds, yep. I know that, RAW, this shouldn't be allowed, but I didn't see a problem realistically or within reason as per the rules? Might there be?