Multiple Funding Sources

<p>I'm looking for ideas on how to allow for multiple funding sources in a project.</p><p>A couple examples:</p><ul><li><strong>Sponsored Work. </strong>Our primary client engages us on a project where some of the funding is provided by an "interested third party" (i.e. a sponsor).</li><li><strong>Shared Engagement. </strong>With some large clients (e.g. state government) we've been asked to allow for two or more groups (in this case autonomous departments) to be billed for either various aspects of an engagement or to share the costs evenly.</li></ul><p>Ideally I need an audit trail that shows a) who got billed what (as separate customers), b) the billing/AR "status" of