If a author-to-be sends a query letter for a story they had a collaboration with, would the agent generally accept them still or wouldn't even bother? If so, how would the two writers send a query letter?
If you work with someone who will be considered a co-creator of the work you include both names on the query.
The first five pages of our novel Potato Vodka Queens Meet Sharkzilla are below. Thank you for your time and consideration.
People who are NOT considered co-creators are paid editors, crit partners, beta readers. If you have any doubts, make sure you clarify with the person ahead of time. I had one unfortunate friend discover that someone he thought was helping him was expecting co-writing credit after the fact. It got sorted out eventually but it sure threw a spanner in the works that we didn't need.