Can a traveler issue a partial refund?

Refunds work at the contribution level — a traveler can refund any individual contribution in full, but can't refund part of a contribution. If you contributed $100 and want $50 back, the traveler would need to refund the full $100 and you'd re-contribute $50.

For most situations, the traveler-cancellation flow (which refunds everyone in full) is the cleanest option.