trellis attrs

Hi,

I would like to have an trellis.component with a trellis.set as one of
its attributes. For instance, (stupid example) suppose a child's first
names will be the first names of all its uncles and aunts. Then I
don't know beforehand how many names the child will get, so I cannot
specify a fixed number of attrs at the beginning of the
trellis.component that represents a child. I tried to achieve this by
using a trellis.set, but then it turns out that each child gets the
same trellis.set, rather than its own. Is there some other way to
resolve this?

Thanks.

Nicky