Thx, Vitor! It turns out that it is even somewhat more complicated: I finally found an explanation in Wilson's 'Simplified Swahili':
[/quote] "...all nouns denoting living beings regardless of class, should be given M- WA- agreements. BUT, there is one exception to this 'rule' and that is with the Personal Possessives only. Within this exception, however, we have to differentiate between humans and animals. 'Humans' which occur in the N class take N class agreement in both the singular and the plural. Animals which occur in the N class (and most do), take M- WA- agreements in the singular, but N class in the plural. [/endquote]
He gives the following examples:
Rafiki yangu amefika, My friend has arrived.
Rafiki zangu wamefika, My friends have arrived.
Mbwa wangu mmoja amefika. My one dog has arrived.
Mbwa zangu wawili wamefika. My two dogs have arrived
I think that last one should be "Mbwa zangu wawili". I see he used the M/WA class prefix for one, so it would make sense to continue using the M/WA class for all the numbers that change with noun class; in this case: wawili, watatu, wanne, wanane. Same for other adjectives: mbwa wangu mkali, mbwa zangu wakali Maybe someone else can comment.