In our Slovenian Biographical lexicon we have pictures of persons, so we use person/figure.
It now turns out we also need pictures with families, i.e. personGrp/figure.
However, personGrp does not allow figures, for no good reason as far as I can see.
I suggest adding model.global to the content model of personGrp, just as it is with person.
There's plenty to improve on in this content model, but it certainly ought to be consistent with that for person. I think this is a corrigible error, so I have corrected it at rev 12860