Business objects, subset of collection

Hi,

I have a collection of business objects that the user works on via
data binding. The user needs to be able to work with a subset of the
collection and I am wondering what the best way to accomplish this is.

Example:

InvoiceCollection->Invoice->PaymentCollection->Payment

The user wants to only work with invoices or payments for a certain
date.

Two ways I can think of are 1) work with a subset, or 2) Work with the
full set in a filtered fashion. I am leaning toward 2), but it gets
quite messy with a bunch of filter related methods in the public
interfaces.

Any help on this would be appreciated.

Thanks,
Jim
.