I'm going to take your post at face value, and set aside your obvious dislike of the mother.
What leapt out to me from your post was
"smelling of sweets" - does he smell of pear drops by any chance?
"extremely sleepy and tired"
"so thirsty"
and
"tired again after very little activity"
All of the above can be symptoms of diabetes. This was exactly how my daughter presented just before being diagnosed with Type 1.
If your son (NOT YOU), doesn't feel able to raise the issue with the child's mother, then if he has parental responsibility (i.e. his name is on the child's birth certificate) then he can take the child for medical attention himself and describe the symptoms and ask for him to be tested.
I would rule out any underlying causes for your grandchild's presentation before leaping to the conclusion that his mother is sabbotaging contact.
You say "We know perfectly well this little GC is not having any routine and from little information forthcoming is fed a series of inadequately-nutritional snacks through the day until 'teatime' and those tea time foods are not adequate for a growing toddler. Certainly, not choke-hazard-sized sweets routinely first thing in the morning or at all. I wonder if crisps are being fed before 'contact' handover...."
Where, exactly, is this information "forthcoming" from? And so what if crisps ARE being fed before contact handover? Maybe not the most desirable snack for a child, but not a cause for alarm.
warped cutting mat - any solutions?
July 23 Limerick (continuation of July 21)