yellowdaisies there's a big difference between being "alone with a child" and sleeping in the same bed without (in this case) the OP's DM there as well. You are hardly comparing apples with apples here! There does NOT have to be an implication of heinous crime, it's to do with norms of society. For example, I would not quite happily share a bed with my BIL, or FIL, even though there is zero chance of anything improper happening, it is just not APPROPRIATE or even normal to want to, if can be avoided. And the bed sharing here CAN be avoided, either by DS having his own bed, or DS and DM sharing. Those two options have been sidestepped for the least normal/favourable option - DS sharing with DMs' partner - WHY?
Becles "On the other hand, you are entitled to whatever qualms you feel as long as you accept this can cause upset and anger in others who in turn feel accused of a heinous crime." What heinous crime has been accused?
OP feels that (quite naturally) it is more appropriate for her DS to sleep with his DGM because (presumably in her opinion) they are closer, and if the OP's DM and her partner normally sleep together I still can't see the need for them sleeping seperately whilst DS is on a sleepover.
If there's two beds, why aren't DM and her partner in one as normal and DS in the other one? If it's because DS wants to share a bed I would think it also natural that the step grandad would not WISH to share a bed with the DS over the DM and would step down from it quite happily.
There is no suggestion of anything improper going on whatsover. It's just about APPROPRIATE behaviour and choosing the most appropriate option as a matter of norm. That is all.