i think an adapter plug would be too much of a strain on the sockets,
which are very susceptible to damage anyway.

mostly i'm happy with multiples, but a y-cable would be better for
those simple splits that we need so often.

here is a better idea, the mega-multiple:

an 8hp panel three columns (a,b and c) of eight sockets.
row 1, columnn a is connected to 1b and 1c, and is also normalled to 2a.
2a is connected to 2b and 2c and is normalled to 3a etc.
putting a plug into 2a disconnects it from 1a.

you now have a very flexible multiple:
eight times 1 into two.
four times 1 into four
two times 1 into eight
one time 1 into 16
and of course combinations of the above.

this wins the award for the most unspectacular module suggestion of
the year, but dieter, i promise you'll be knighted if you build it.

cheers,

stu